BBC Sky at Night 2013-11

STARGAZING ASTROPHOTOGRAPHY LATEST KIT SKILLS THE BIGGEST NAME IN ASTRONOMY

Sky at Night SPECIAL ISSUE

COMETS THE COMPLETE STORY u See comet ISON brighten this month! u Discover where comets come from u Life on Earth: did comets kick it off?

Putting Pluto in its place A fresh framework for what makes a planet

The demon of autumn The secrets of variable star Algol

ALSO IN THIS ISSUE ON TEST: The eyepiece that redefines wide-field views

Make a smartphone holder for your scope New ways to search for life in our Solar System 15-page guide to this month’s night sky NOVEMBER 2013 #102 www.skyatnightmagazine.com

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LETTER FROM THE EDITOR NOVEMBER 03

Welcome

This month’s contributors include...

The month we have all been waiting for has arrived

STUART CLARK ASTRONOMY AUTHOR

The winner of this year’s European Astronomy Journalism prize looks at new ways of searching for life in our Solar System. HEATHER COUPER SCIENCE BROADCASTER

Heather squares off with a demon as she unravels the mysteries of variable star Algol, which is high in the sky all month. STEVE RICHARDS DEEP-SKY OBSERVER

Steve turns his attention to Auriga and Orion to bring you six of the region’s best observing targets in this month’s Deep-sky tour. PAUL SUTHERLAND SCIENCE WRITER

Paul gets his head around the Oort Cloud, a proposed source of comets that we’ve never seen, nor have any evidence for.

While astro imagers and professional observatories have been watching comet C/2012 S1 ISON for a few months now, as it nears the Sun during November we’ll finally find out whether this 5kmwide aggregation of ice and rock will brighten enough to become visible to the naked eye. Share the excitement this issue: Pete Lawrence brings us full observing details in The Sky Guide on page 50, tips on how to photograph it on page 60, and the story of its discovery and journey to the inner Solar System on page 33. To mark the occasion, on page 74 Will Gater examines fresh research that sheds new light on the theory that comets brought the chemical building blocks of life to Earth, while on page 78 Paul Sutherland looks at the mysterious region at the edge of the Solar System from which some comets – including ISON – are thought to come. I for one am really looking forward to seeing the comet on its only ever visit from deep space to the inner planets! Back here on Earth, and following the recent speculation regarding the future of The Sky at Night TV programme, the latest we’ve heard from the BBC is that the programme is on air until the end of the

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year and plans for subsequent series are being discussed. I’d like to reassure everyone that BBC Sky at Night Magazine will continue to be at the forefront of astronomy and at the heart of the discussion. We’ve got all sorts of plans to do even more to satisfy your thirst for knowledge and look forward to your continued support. Enjoy the issue.

Chris Bramley Editor

PS Next issue goes on sale 21 November.

Sky at Night LOTS OF WAYS TO ENJOY THE NIGHT SKY...

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Find out what The Sky at Night team will be exploring in this month’s episode on page 19

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04 CONTENTS NOVEMBER

In the magazine ON THE COVER 33

33

NEW TO ASTRONOMY? See The guide on page 78 and our online glossary at www.skyatnightmagazine.com/dictionary

THE WORLD WAITS FOR ISON

81

16 FIRST LIGHT

62

94 40

47

CHEMICAL COURIERS?

FEATURES

REGULARS

06 Eye on the sky

11 Bulletin

Stunning new images of space.

COVER IMAGE: MARK GARLICK, THIS PAGE: DETLEV VAN RAVENSWAAY/SCIENCE PHOTO LIBRARY, TAKE 27 LTD/SCIENCE PHOTO LIBRARY, WWW.THESECRETSTUDIO.NET

72

90

78 Skills 78 The guide The Oort Cloud.

The latest astronomy and space news.

81 How to

33 The world waits for ISON

19 What’s on

Make a smartphone adaptor.

Your guide to observing comet C/2012 S1 ISON, including key dates, magnitudes estimates and more.

Astronomy events from around the UK.

85 Sketching Drawing NGC 7332.

20 Sky at Night diary 87 Scope doctor 40 Chirality: the new search Your backstage pass to the TV show. 89 Reviews for life in the Solar System 22 Interactive First Light We take a peek at the new technology that could change the way we explore nearby planets and moons.

62 The demon of autumn Discover the secrets of Algol, the best beginner variable star in the night sky.

69 Skylab: the final mission Relive the last days of America’s first space station, the ill-fated and accident prone Skylab.

72 Comets: chemical couriers? We investigate theories that comets could have seeded Earth with the vital ingredients for life.

skyatnightmagazine.com 2013

Your letters, emails and tweets.

26 SUBSCRIBE

90 Starlight Xpress Trius-H814 CCD camera.

Get your issues at a discount

94 Explore Scientific

28 Hotshots

98 Starlight Xpress Mini

The very best of your astro images.

47 THE SKY IN NOVEMBER Your 15-page guide to the night sky featuring our pick of the top sights, an all-sky chart, a deep-sky tour and much more…

9mm 120 º eyepiece. Filter Wheel with OAG.

102 Books 104 Gear

106 What I really want to know is… Can black holes affect a galaxy’s size?

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AVAILABLE NOW ON iTUNES – ONLY £3.99 To download visit www.skyatnightmagazine.com/man-in-space-ipad-app skyatnightmagazine.com 2012

and Land water of

wind

ESA/DLR/FU BERLIN (G. NEUKUM)

A four-image mosaic reveals how the elements have left their mark on the Red Planet MARS EXPRESS SPACECRAFT, 5 SEPTEMBER 2013 The customarily sand-coloured surface of Mars is tarnished by a vast sooty blemish in this exceptional image taken by the High Resolution Stereo Camera on ESA’s Mars Express orbiter.

The star of the scene is 167kmwide, 35km-deep Becquerel, the largest crater in this image. The dark material is not thought to be local: instead it is thought to have been swept into

and around the crater by powerful winds, perhaps from a volcanic eruption. Becquerel reveals not just a history of the Red Planet’s weather patterns, but its

now-exhausted supply of liquid water. Rising from the ashes is a 1km-high mound of lightcoloured sulphate deposits – the presence of which suggests there may once have been a lake here.

FRANCE) FOR THE GOULD BELT SURVEY KEY PROGRAMME, NASA/ESA/THE HUBBLE HERITAGE TEAM (STSCI/AURA)/IPHAS

ESO, NASA/SDO, NASA/JPL/UNIVERSITY OF ARIZONA, ESA/HERSCHEL/PH. ANDRÉ/V. KÖNYVES/N. SCHNEIDER (CEA SACLAY,

08

S Gallant glow EUROPEAN SOUTHERN OBSERVATORY 26 AUGUST 2013 ESO’s Very Large Telescope peered into the heart of emission nebula NGC 6357 to capture this ethereal image. This stellar soup is home to vast clouds of gas, streams of dark dust, and nurseries of newborn and still-forming stars. The nebula is inundated by intense ultraviolet radiation from nearby open star cluster Pismis 24, which it re-emits as visible red light.

Our explosive Sun X  SOLAR DYNAMICS OBSERVATORY 18 AUGUST 2013 A medium-sized solar flare erupts from the Sun, shooting a coronal mass ejection (CME) into space in this vivid shot from NASA’s Solar Dynamics Observatory. The CME can be seen streaming from the edge of the Sun.

skyatnightmagazine.com 2013

EYE ON THE SKY NOVEMBER 09

W Radiant Orion

T Climate change

HERSCHEL SPACE OBSERVATORY 26 AUGUST 2013

MARS RECONNAISSANCE ORBITER 8 AUGUST 2013

The Orion Nebula glows brilliantly at the centre of this image from ESA’s Herschel Space Observatory. More massive stars are being born in this part of the Orion A star-formation cloud than anywhere else, which is why the nebula appears so bright in this infrared image.

The geological process of ‘cyclic bedding’ could be on show in this shot of a crater in Mars’s Arabia Terra. Cyclic bedding refers to the pattern caused by changes in the amount of sediment available to create new layers of rock; these fluctuations are the result of climate changes spanning millions of years.

Lightyear-long larva HUBBLE SPACE TELESCOPE 29 AUGUST 2013 At over a lightyear in length, this twisted mass of interstellar gas and dust floats in space like a giant, cosmic caterpillar. This vast celestial object, a protostar just beginning to evolve, has been sculpted into its larva-like shape by powerful radiation from nearby stars.

skyatnightmagazine.com 2013

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BULLETIN NOVEMBER 11

Bulletin The latest astronomy and space news written by Hazel Muir

PLUS

CUTTING EDGE

Our experts examine the hottest new astronomy research papers CHRIS LINTOTT LEWIS DARTNELL

14 16

Comment

by Chris Lintott

Voyager 1 is our most distant space probe – its signals take 17 hours to reach Earth

Voyager reaches interstellar space

NASA/JPL-CALTECH

The probe finally enters a new frontier after months of speculation NASA’S VOYAGER 1 spacecraft has officially become the first probe to venture into interstellar space. Scientists hope it will continue to beam back data about this enigmatic region until at least 2020. Voyager 1 was launched in September 1977 to study the planets Jupiter and Saturn. As it continued its outward journey, scientists anticipated that it would eventually leave the region where particles streaming out from the Sun hold sway and instead encounter the ionised gases, or plasma, expected to exist in interstellar space. In September, scientists finally confirmed the probe had made it. “Readings over the past year showed that solar particles had essentially all left and galactic particle intensities increased dramatically,” says team member Matthew Hill from the Johns Hopkins University in Maryland.

Voyager 1’s instruments allowed the team to make a complicated assessment of vibrations in the plasma that confirmed a sharp increase in electron densities in the spacecraft’s environment. A thorough comparison with older data suggested it first entered interstellar space in August 2012, at a distance of around 121 AU from the Sun. The Earth-Sun distance is 1 AU. “We believe this is humankind’s historic leap into interstellar space,” says Voyager project scientist Ed Stone from the California Institute of Technology. “The Voyager team needed time to analyse those observations and make sense of them. But we can now answer the question we’ve all been asking – ‘are we there yet?’ Yes, we are.” > See Comment, right

This latest milestone in Voyager’s journey is certainly worth celebrating, yet at the same time the exact moment it crossed the heliopause is no more significant than the difference in Earth’s position either side of the fireworks on New Year’s Eve. After all, the veteran spacecraft is still closer to the Sun than it is to the Oort Cloud, the vast, spherical reservoir of comets hypothesised to lie in the outer Solar System. It’ll take another 30,000 years to pass through – and for all of that time the most important force on it will still be the gravitational pull of the Sun. That said, I don’t intend to rain on the Voyager team’s well-deserved parade. It is remarkable that the spacecraft has travelled so far, but what’s really worth raising a glass to is the fact it’s still alive to send back details of its new adventure. Some of Voyager’s most significant science may still lie ahead of it as it travels through the strange new realm in which it finds itself. CHRIS LINTOTT presents The Sky at Night on BBC TV

skyatnightmagazine.com 2013

12

Titan’s ice shell may have roots

ESA/NASA/JPL/UNIVERSITY OF ARIZONA, THINKSTOCK, ESO/NASA/JPL-CALTECH/M. KORNMESSER/R. HURT, NASA/JPL-CALTECH, NASA/JPL, NASA/JPL-CALTECH

Odd gravity data hints at unusual ice deposits beneath the moon’s mountains

News in brief ARE WE ALL ALIENS? Could life on Earth have originated in space? New experiments have added to evidence that it may be a possibility. Panspermia is a fringe theory that suggests primitive life arose in space and was brought to Earth by meteorites. Yet it has been unclear whether microbes could survive the violent impact on our planet’s surface. To find out more, Dina Pasini from the University of Kent fired single-celled algae into water at the high speeds typical of meteorite impacts. “Even at 6.93km/s, a small proportion survived,” she says. “This sort of impact velocity would be what you would expect if a meteorite hit a planet similar to the Earth.”

Titan’s peaks – imaged by the Huygens probe back in 2005 – could hide giant icebergs that extend down to an ocean

THE ICE SHELL that covers the surface of Saturn’s moon Titan may be thicker and more rigid than previously thought, and could even have deep ‘roots’ that extend into a global subsurface ocean. That’s the interpretation of new data from NASA’s Cassini spacecraft, which has revealed an odd relationship between the moon’s topography and its gravity. Cassini’s measurements indicate that Titan’s surface elevation varies by about 160m over very large scales. Planetary scientists Douglas Hemingway and Francis Nimmo from the University of California, Santa Cruz, discovered that higher regions have lower gravity than low-lying ones. “Normally, if you fly over a mountain, you expect to see an increase in gravity due to the extra mass of the mountain,” says Nimmo. “On Titan, when you fly over a mountain the gravity gets lower. That’s a very odd observation.” The researchers say the best explanation is that higher parts of the moon’s surface sit atop deep roots a bit like icebergs, which extend into a water skyatnightmagazine.com 2013

ocean suspected to lie far below the surface. “Because ice is lower density than water, you get less gravity when you have a big chunk of ice there than when you have water,” says Nimmo. It’s thought that the buoyancy of each icy root pushes it up against the outer ice sheet, creating a slightly higher surface elevation. “It’s like a big beach ball under the ice sheet pushing up on it, and the only way to keep it submerged is if the ice sheet is strong,” says Hemingway. “It means that Titan’s ice shell must have a very thick rigid layer.” They estimate that the outer ice shell must be at least 40km thick to keep the buoyant roots submerged. The scientists also suggest that the elevated regions would be much higher due to the large roots were it not for constant erosion of Titan’s surface. “Weather and erosion are acting on it, moving stuff around and redepositing sediments,” says Nimmo. However, it’s still not clear what process would have created the deep roots in the first place. www.nasa.gov/cassini

PEOPLE POWER REVEALS PULSARS Using the power of 200,000 private PCs, a project called Einstein@ Home has uncovered 24 new pulsars in the Milky Way. Pulsars are superdense neutron stars sometimes left behind when massive stars explode. Using a supercomputer that harnessed processing time from home and office computers offered by volunteers, scientists pinpointed the pulsars in data from the Parkes Radio Telescope in Australia. Einstein@Home allowed the Parkes data to be analysed in eight months – a single CPU would have taken 17,000 years.

BULLETIN NOVEMBER 13

TASTY TREAT AT THE HEART OF THE MILKY WAY News in brief THE CENTRAL BULGE of our Galaxy has a curious peanut-like shape when viewed from certain angles, say astronomers who have made the best 3D map yet of the central Milky Way. Two teams of researchers used data collected by ESO telescopes in Chile to determine the shape of the bulge, which contains roughly 10 billion stars. “The inner region of our Galaxy has the shape of a peanut in its shell from the side and of a highly elongated bar from above,” says study co-author Ortwin Gerhard from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. “It is the first time that we can see this clearly in our own Milky Way.” Computer simulations suggest the shape is typical of a barred galaxy that started out as a disc of stars, the inner part of which later buckled. www.mpe.mpg.de

JPL UNVEILS AUTONOMOUS ROVER CAMERA

Similar peanut structures have been seen in other galaxies

Black holes may starve their galaxies

A new camera developed by NASA’s Jet Propulsion Laboratory (JPL) could change the exploration of distant worlds. TextureCam, shown below, can do more than take pictures – it can also analyse the rocks in its images and independently decide whether to keep exploring the same site or move on, without wasting time waiting for instructions from Earth. “If you want to get ambitious and go to Europa, asteroids and comets, you need autonomy to even make that feasible,” says JPL’s Kiri Wagstaff, one of the camera’s developers.

High-energy jets could remove the raw materials needed for new stars

NASA NARROWS LANDER SITES

The jets spewed out of black holes could remove vast quantities of gas

ASTRONOMERS HAVE FOUND fresh evidence that supermassive black holes in the centres of galaxies can blow away massive amounts of gas – enough to curb the formation of new stars. Many galaxies have fewer stars than theory predicts. One explanation for this is that much of the galaxy’s gas, the raw material for star formation, is pushed out by the high-energy jets of particles from supermassive black holes. Now, while examining a galaxy nearly 1.5 billion lightyears away, a team led by Raffaella Morganti from the Netherlands Institute for Radio

Astronomy and the University of Groningen has spotted vast clumps of cold hydrogen moving outward ahead of black hole jets at 1,000km/s. One of the clouds is 140,000 times as massive as the Sun. “This is the most definitive evidence yet for an interaction between the swift-moving jet of such a galaxy and a dense interstellar gas cloud,” says Morganti. “We believe we are seeing in action the process by which an active, central engine can remove gas from a young galaxy.” www.astron.nl

NASA has pinpointed four possible landing sites for its next mission to the Martian surface. The InSight lander, due to launch in March 2016, will gather seismic data from the Red Planet. All four potential sites lie on an equatorial plain in an area called Elysium Planitia. “We picked four sites that look safest,” says Matt Golombek from NASA’s Jet Propulsion Laboratory in California. “They have mostly smooth terrain, few rocks and very little slope.”

skyatnightmagazine.com 2013

14

CUTTING EDGE

Our experts examine the hottest new research

The secrets of the fleeting flickers If we want to learn more about distant galaxies, perhaps we should look towards our own WORDS: CHRIS LINTOTT Sagittarius A* is a surprisingly quiet black hole, with faint X-ray emissions

X-ray close-up

short as 10 minutes. They conclude that whatever is powering these changes must be coming from a tiny region, probably just a few times as large as the ‘Schwarzschild radius’ (which serves as the ‘size’ of the black hole itself). There are also signs that the physics controlling things on such small timescales extends out into the surrounding material. The typical timescale – the average length of a submillimetre

X-ray and infrared

X-RAY: NASA/UMASS/D.WANG ET AL., IR: NASA/STSCI

S

ometimes astronomers can seem remarkably myopic. Given an entire Universe, filled with hundreds of billions of galaxies, it seems slightly ridiculous to concentrate on only one, our own Milky Way, simply because we happen to find ourselves within it. Some excellent science can come out of these parochial searches, though, as in this month’s paper. A team led by Jason Dexter from the University of California, Berkeley, took a hard look at the behaviour of the supermassive black hole that lurks at the centre of the Milky Way, which is surprisingly quiet compared to those in galaxies similar to our own. One of the nice things about studying our black hole – known as Sagittarius A* – is that near it things change on short timescales, something which is rare for astronomers used to dealing in millions or billions of years. And over the 10 years of observations reported in the paper, Dexter and colleagues saw a flickering of light as material fell towards and eventually into it. The light in question is being emitted in what astronomers call the ‘submillmetre’ region of the electromagnetic spectrum, which to anyone else corresponds to microwaves of the approximate frequency used in your kitchen. This is the part of the spectrum where the material drawn into the black hole shines brightest, but it also sits between the infrared and radio. We know that Sagittarius A* can suddenly flare in the infrared, brightening over the course of 30 minutes or so, and establishing any connection between this and the radio behaviour is essential in understanding just what’s going on. The results are somewhat surprising, finding consistent flickering in brightness on timescales as skyatnightmagazine.com 2013

“These timescales are in line with what we would expect from quasars, the systems with the most active black holes of all”

Chris Lintott is an astrophysicist and co-presenter of The Sky at Night on BBC TV. He is also the director of the Zooniverse project

flicker – is about eight hours, sitting nicely between that seen in infrared and radio. If this all sounds a little confusing, that’s because we don’t really understand much about what’s going on so close to a black hole. There is hope, however. Once you account for the fact that the Sagittarius A* is unaccountably quiet, these timescales are in line with what one would expect from studies of quasars, the systems with the most active nuclear black holes of all. Our galactic navel-gazing, therefore, seems justified, as by studying what’s close to home we can understand what’s going on throughout the Universe. Right now astronomers are focused on a cloud of gas and dust that’s making repeated close passes to Sagittarius A* over the next few years; this paper, among others, gives us hope that as well as putting on a spectacular show, its fate should provide real insight.

CHRIS LINTOTT was reading… An 8-hour characteristic time-scale in submillimetre light curves of Sagittarius A* by Jason Dexter et al Read it online at http://arxiv.org/abs/1308.5968

BULLETIN NOVEMBER 15

News in brief

Hubble spies huge pool of ancient stars The group of globulars is twice as populous as any seen previously

University College London has published an online archive of historic space images. The pictures include Soviet photos of the surface of Venus, hand-assembled mosaics of Jupiter’s moons and an extremely detailed lunar map that’s more than a century old. Many of the rare photos and maps have never been available online until now. Some originated as hard copies shipped out of the US by NASA before the internet became a major tool for sharing scientific data – University College London was one of only seven institutions outside the US to receive them. To browse through them, visit www.ucl.ac.uk/mapsfaculty/space-history

NASA LAUNCHES MOON ORBITER On 7 September, NASA successfully launched its lunar orbiter LADEE (Lunar Atmosphere and Dust Environment Explorer). The spacecraft will orbit the lunar equator for 100 days to study the Moon’s thin outer atmosphere, as well as dust in its vicinity.

Abell 1689 contains 160,000 globular clusters; our Milky Way is home to a paltry 150

matter,” says team member Karla Alamo-Martinez from the Center for Radio Astronomy and Astrophysics of the National Autonomous University of Mexico. www.hubblesite.org

WISE SPACECRAFT TO HUNT KILLER ASTEROIDS

WISE is being brought out of retirement for a new mission

Looking back

UCLS, NASA/AMES, NASA/ESA, J. BLAKESLEE (NRC HERZBERG ASTROPHYSICS PROGRAM/DOMINION ASTROPHYSICAL OBSERVATORY) AND K. ALAMO-MARTINEZ (NATIONAL AUTONOMOUS UNIVERSITY OF MEXICO), NASA/JPL-CALTECH X 2

RARE SPACE IMAGES GO ONLINE

THE HUBBLE SPACE Telescope has uncovered the largest population of globular clusters ever found. The observations revealed roughly 160,000 of them in the crowded core of Abell 1689, a galaxy cluster some 2.2 billion lightyears away in Virgo. The astronomers who made the discovery say the bonanza of clusters, some as dim as 29th magnitude, can help determine the amount of dark matter within huge galaxy clusters like this one. “If you know how many globular clusters are within a certain distance [of a galaxy cluster’s centre], we can give you an estimate of the amount of dark

NASA HAS REACTIVATED its Wide-field Infrared Survey Explorer (WISE) spacecraft to look for menacing asteroids that might hit the Earth. Launched in 2009, WISE surveyed asteroids, stars and galaxies before being placed in hibernation. NASA revived the spacecraft in September to characterise space rocks that come within 45 million km of Earth’s orbit round the Sun. It’s thought that this extended mission could see WISE analyse more than 2,000 near-Earth objects – and perhaps spot suitable candidates for the agency’s ambitious asteroid capture and relocation plan. ww.nasa.gov/wise Mars Global Surveyor surpassed all expectations

The Sky at Night November 1996 On 10 November 1996, the Sky at Night broadcast discussed three upcoming missions to Mars: NASA’s Mars Global Surveyor and Mars Pathfinder, and Russia’s Mars 96. By the time of the broadcast, NASA had already launched Mars Global Surveyor, which lifted off on 7 November. It turned out to be spectacularly

successful, completing its primary mission in January 2001 and continuing to operate until 2006. Mars Pathfinder, likewise, had an excellent outcome. It launched flawlessly on 4 December 1996 and became the first successful Martian lander since the two Viking probes touched down on the Red Planet in 1976.

Mars 96 was less lucky. This extremely ambitious project carried many international instruments and included an orbiter, surface stations and surface penetrators. However, its launch on 16 November 1996 failed, and it broke up over the Pacific and South America.

skyatnightmagazine.com 2013

16 BULLETIN NOVEMBER

CUTTING EDGE

Our experts examine the hottest new research

We need to talk about Pluto A fresh look at what makes a planet ‘a planet’ could result in a more crowded Solar System WORDS: LEWIS DARTNELL The framework could see Pluto, illustrated here with its moon Charon, become a planet once more

where they formed in the protoplanetary disc. These are the terrestrial planets (inner rocky worlds like Earth), the Jovian planets (the gas and ice giants), the asteroid belt or ‘Cerian’ planets (such as Ceres), and the Kuiperian planets (like Pluto). If, at some point in the future, icy objects large enough to be spherical are discovered in the Oort cloud, hypothesised to lie around 50,000 times farther

DETLEV VAN RAVENSWAAY/SCIENCE PHOTO LIBRARY

I

n August 2006, the International Astronomical Union (IAU) made a decision that would create controversy – it made a change to the formal definition of what makes a planet ‘a planet’, resulting in the demotion of Pluto to a ‘dwarf planet’. The thinking behind this was that as more bodies were discovered in the Solar System, and in particular in the cold outer hinterland beyond Neptune, it became clear that there were more and more Pluto-like objects out there and the traditional classification system was no longer workable. The criteria declared by the IAU were that a planet must: a) orbit the Sun; b) be large enough to have been pulled into a sphere by its own gravity; and c) have cleared its orbital neighbourhood of other bodies. On the face of it this adequately delineates the remaining eight planets from asteroids like Ceres and Vesta, or Kuiper-Belt objects like Pluto, Eris and Makemake. But there is still a great deal of uneasiness in the astronomical community with the way things have been left. If Earth or any of the other small rocky terrestrial planets were to swap places with Pluto, they also would be unable to clear their orbital environs of other objects, and so would fail the planet classification. So David Russell of the Owego Free Academy in New York has proposed a new classification system for the Solar System – and it’s good for extrasolar systems too, once the exoplanets have been characterised in enough detail. This system, he says, addresses the shortcomings of the IAU’s decision. Russell keeps the requirements for spherical objects larger than 400km in diameter orbiting the Sun, but argues for four subcategories of planets based on skyatnightmagazine.com 2013

“If Earth or any of the other small terrestrial planets were to swap places with Pluto, they would also fail the planet test”

Lewis Dartnell is an astrobiologist at the University of Leicester and the author of Life in the Universe: A Beginner’s Guide

from the Sun than Earth, Russell says that a fifth category can simply be added: the Oortians. Under this proposal, all the planets of the Solar System are considered equal, just with different physical or orbital characteristics. Russell’s scheme offers four terrestrial, four Jovian, four Cerian and 15 Kuiperian planets (possibly 24 if several recently discovered objects are found to qualify) – boosting the total number of planets to at least 27. And bear in mind that while all the terrestrial, Jovian and Cerian worlds have already been found, we are likely to spot more and more large trans-Neptunian objects – so the planet tally is likely to increase substantially. While this proposal certainly allows for a clear, cut-and-dry definition of what makes a planet, it is perhaps too inclusive for many astronomers – time will tell how much support it will attract.

LEWIS DARTNELL was reading… A Proposal for New Definitions of Solar System Bodies – Planet, Moon and Satellite by David G Russell Read it online at http://arxiv.org/abs/1308.0616

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NOW L I M I TE T IC K E T D AVAIL A S BL E

Damian Peach Damian is arguably the most famous planetary imager in the world. His breathtaking images push the boundaries of what amateur equipment can achieve. Jupiter is the focus of Damian’s talk as he explains the best way to image the Gas Giant.

Damian Peach, Pete Lawrence and Steve Richards share their top imaging tips during an evening of unmissable lectures

Pete Lawrence Pete is best known for his spectacular lunar and solar images. He is a reporter on BBC TV’s The Sky at Night and writes BBC Sky at Night Magazine’s monthly Sky Guide. Pete will discuss how to capture our closest celestial neighbour, the Moon.

@BRISTOL

Steve Richards Steve’s passion is deep-sky imaging from his home close to the UK’s south coast. He is BBC Sky at Night Magazine’s expert scope doctor and writes regular articles on astro-imaging equipment and techniques. On the night Steve will be sharing his tips on imaging nebulae.

Don’t miss your chance to join us for an evening of lectures from three masters of astrophotography. As part of BBC Sky at Night Magazine’s series of lectures, world-renowned imagers Damian Peach, Pete Lawrence and Steve Richards will reveal how you can capture and process your own spectacular planetary, lunar and deep-sky shots. On the evening we’ll be in the unforgettable surroundings of the At-Bristol science centre, on the waterfront in the heart of Bristol. Each speaker will give a 30-minute talk exploring their particular area of astro imaging expertise. The lectures will be followed with a Q&A session, before the evening concludes with an opportunity to meet with the speakers over a glass of wine.

LECTURE DETAILS Date Tuesday 12 November Venue At-Bristol science centre, Anchor Road, Bristol, BS1 5DB Order of events 6.30pm Doors open 7.30pm Lectures begin 9pm Question and answer session with the experts 9.30pm Drinks reception Ticket prices Subscribers £20 Non-subscribers £25

Don’t miss out – order your tickets today

www.skyatnightmagazine.com/masterclass or call our order hotline on 0844 871 8819

†

BBC Sky at Night Magazine reserves the right to replace the speakers with an alternative of equal stature in the unlikely event that any of them are unable to attend. Please let us know when booking of any special access requirements. Please have your subscriber number to hand when booking. Tickets are non-refundable and places are limited. †Calls to this number from a BT landline will cost no more than 10p per minute. Calls from mobiles and other providers may vary. Lines are open 24 hours a day, seven days a week.

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WHAT’S ON NOVEMBER 19

What’s on

Our pick of the best events from around the UK

Apollo: For All Mankind Science Museum, London, 12 November, 7.30pm

PICK

OF THE MONTH

Weather on Other Planets: Measurement and Interpretation British Interplanetary Society, London, 6 November, 1.30 to 5.30pm From orbiting satellites to robotic landers and rovers, there are many ways to monitor the weather on other planets. Hear a host of space scientists and meteorological experts discuss how the climate on distant worlds is both measured and observed at this month’s British Interplanetary Society lecture. Go online to book your place. www.bis-space.com

Dalby Forest Star Party Dalby Forest Visitor Centre, Pickering, 1 November 2013, 8pm

NASA, NASA/JPL-CALTECH/SPACE SCIENCE INSTITUTE, FORESTRY COMMISSION/© CROWN COPYRIGHT/ © TONY BARTHOLOMEW, DAVE THOMPSON/COUNTY DURHAM

Join Scarborough and Ryedale Astronomical Society for an evening of stargazing under the dark skies of Dalby Forest on the southern fringes of the North Yorkshire Moors National Park. There’s no need to bring a scope, as the society will be providing a range of astronomical equipment. Contact [email protected] for more information or visit www.scarborough-ryedale-as.org.uk Experience the Apollo programme in a whole new way at this one-off performance

Kielder Forest Star Camp

The Science Museum’s IMAX theatre will reverberate to the sound of contemporary orchestra Icebreaker on the 12th, when they perform their version of Brian Eno’s space-themed masterpiece Apollo: Atmospheres and Soundtracks. Set alongside footage from Al Reinert’s 1989 film For All Mankind – a production that has long been considered one of the best documentaries ever made on NASA’s Apollo space programme – the

Kielder Forest, Northumberland, 30 October to 4 November 2013

orchestra will turn the original electronic soundtrack into a vibrant reworking, attempting to capture the awe-inspiring excitment surrounding the US’s first trip to the Moon. Tickets cost £19 and can be booked online or by calling 0870 870 4868. If you can make it there early, head into the main museum and take a peek at the Apollo 10 command module. www.sciencemuseum.org.uk

BEHIND THE SCENES THE SKY AT NIGHT IN NOVEMBER and

One, 3 November, around midnight (repeated Two, 9 November, midday)*

Four, 4 November, 8pm;

MOORE MOON MARATHON Sir Patrick Moore spent a lifetime studying the Moon, so the Moore Moon Marathon observing challenge was created in his honour. This month the Sky at Night team catch up on the results and pay a visit to Flamsteed Astronomical Society to report on a penumbral lunar eclipse. During a penumbral eclipse, the outer part of Earth’s shadow passes over the Moon

Now in its 11th year, Kielder Forest Star Camp has built a reputation as one of the northeast’s premier astronomy events. With around 150 amateur astronomers from across the country expected to attend, the event will combine exquisite stargazing – Northumberland has the largest area of dark sky in England – with a programme of talks covering incoming comet C/2012 S1 ISON, eclipse chasing and more. Pitches cost £12 per night. For more information go to www.kielderobservatory.org

*Check www.radiotimes.com as times may vary

MORE LISTINGS ONLINE Visit our website at www. skyatnightmagazine.com/ whats-on for the full list of this month’s events from around the country. To ensure that your talks, observing evenings and star parties are included, please submit your event by filling in the submission form at the bottom of the page.

skyatnightmagazine.com 2013

20

diary While the rest of the Sky at Night team heads to a star party, Paul Abel travels to London for a showdown with ‘the Man who Killed Pluto’

BBC, PAUL ABEL X 3

A

s I write this, it’s September and we’re shifting from summer to autumn. This period around the autumn equinox marks the start of longer (colder) nights and, this time round, the return of Jupiter and Mars in the night sky. This month, the Sky at Night team got set to cover a star party and the European Planetary Science Conference in London – for its loyal viewers. First came the star party. Now I am no lover of camping; actually, let me rephrase that: I hate it with a passion that can be measured in solar masses. My last experience at Kielder still looms large in my mind, in particular the horror of erecting our own tents. Naturally Pete Lawrence was able to get his assembled without too much trouble, as were the other members of the crew. Alas mine looked like a modern art sculpture,

Paul was much more at home in London – where there was not a tent in sight

which I subsequently named ‘misery’. Moreover, it would have been nice to know that fly sheets aren’t optional, they really do help to keep the rain out...

Happy campers

Posters form a large part of many conferences

skyatnightmagazine.com 2013

Anyhow, for this particular star party Pete, Chris Lintott and Lucie Green went off to the Brecon Beacons, while I happily escaped to London to cover the conference. The Beacons are situated in rural Wales and are home to some of the darkest skies in the UK. For the past few years, the site has hosted a small

but enthusiastic star party in September, called Star Camp. Camping aside, it’s not hard to understand the attraction of star parties. Away from the light pollution of towns and cities, the night sky loses its orange glow and is transformed into a breathtaking vista; a black velvet sheet powdered with the lights from thousands of stars. In these conditions the Milky Way blazes overhead; the distant spiral arm of the Galaxy has structure – it is clearly split into two parts in Cygnus and the knotty star clouds of Sagittarius look magnificent. Even the smallest telescopes will reveal scenes both enchanting and alien under these rare circumstances. This was the scene our intrepid gang were hoping to capture.

>

BEHIND THE SCENES NOVEMBER 21

Lucie reported that the first night was indeed clear and everyone was able to marvel at the skies above. The Brecon Beacons lived up to its name and Pete managed to capture a superb image of the Milky Way, meandering its way through the summer constellations. The next day however, the usual Sky at Night weather returned and brought heavy rain throughout much of the day and all of the night. Our producer Jane Fletcher is always ready with a plan, and so the team recorded a rather different Space Surgery, this time as a Q&A with the good people attending the star camp. Lucie and Pete also took the time to explain the intricate subtleties of an equatorial mount, and why you might age a fortnight in just a few hours if you try and do photography without one.

only professional astronomers who were displaying the products of their latest research – a small team from the British Astronomical Association who had done some wonderful Paul and Mike asteroid work also had Brown talk a poster on display. reclassification The first interview of the morning was with Prof Dave Jewitt of the University of California, Los Angeles. Dave was working on a fascinating object recently discovered within our Solar System: an asteroid that behaves like a comet. As this asteroid approaches the Sun, the increasing heat from the our star causes ices deep within

“This was not a demotion but a reclassifying, a process that is a core philosophy of science” Meanwhile, my train slowly pulled into St Pancras at 7.30am, under a forebodingly dark ceiling of grey cloud. I made my way to University College London, home of the European Planetary Science Congress. For a week in early September, some of the biggest names in planetary science would be here, and my aim was to interview as many as possible to give a feel of what’s going on in the field, as well as what a conference is like.

Pluto’s peril I located Jane and the crew and headed into the conference. The first thing we did was capture some of the many splendid posters on display – posters that were designed to give visitors an overview of what the different scientific teams across the world were working on. They were wonderfully diverse and ranged from the composition of the oceans on Titan to novel ways of detecting planets orbiting distant stars. And it was not

the asteroid to sublimate, giving off gas rather like a cometary tail. However when it returns to colder climes, it looks for all the world like an asteroid once more. A few of these objects have been discovered and they are still something of a mystery. Up next was Prof Mike Brown from Caltech. Mike might be more familiar to you as ‘the Man who Killed Pluto,’ for it was he who was most influential in removing Pluto’s planetary status. As we spoke before the cameras it was obvious why Pluto had it coming. In that ancient frozen ring of debris known as the Kuiper Belt, there are objects (like Eris for example) that are bigger than Pluto or of similar size. If Pluto had to be a planet then so did many more objects. It became clear that Pluto was a great example of a new class of object: a dwarf planet. To be honest, this was not a demotion but a reclassifying, a process that is a core philosophy at the heart of science. I have to confess to you, after the interview, my loyalty to Pluto melted away like a chocolate fireguard.

The last scientist we filmed was Dr Simone Marchi, who works on NASA’s DAWN mission. Simone is also involved in ESA’s deeply ambitious Rosetta mission, designed to study the comet 67P/Churyumov–Gerasimenko (I can’t pronounce it either). ESA wants to put a lander on the surface of this comet, surely one of the most inhospitable environments any spacecraft made by human hands has ever been to. One can’t help but wonder what surprises await the lander on the volatile surface of this comet. As we wrapped up filming for the day, I couldn’t help but reflect on how our view of asteroids and comets had changed over the past decade or so. They are no longer inert lumps of rock, frozen and drifting in the cold murky depths of space, but rather dynamic objects that might turn out to be the Rosetta Stones of our Solar System. S

THE SKY AT NIGHT IN NOVEMBER One, 3 November, around midnight (repeated Four, 4 November, 8pm; and Two, 9 November, midday)*

MOORE MOON MARATHON Sir Patrick Moore spent a lifetime studying the Moon, so the Moore Moon Marathon was created in his honour. This month the Sky at Night team catch up on the results and visit to Flamsteed Astronomical Society to report on a penumbral lunar eclipse. *Check www.radiotimes.com as times may vary

skyatnightmagazine.com 2013

22

Interactive EMAILS s LETTERS s TWEETS

This month’s Email us at [email protected] top prize: four Philip’s books The ‘Message of the Month’ writer will receive four top titles courtesy of astronomy publisher Philip’s. Heather Couper and Nigel Henbest’s Stargazing 2013 is a month-by-month guide to the year and you’ll be able to find all the best sights with Patrick Moore’s Guide to the Night Sky. Stargazing with Binoculars by Robin Scagell and David Frydman contains equipment and observing guides, and you’ll be viewing planets, galaxies and more with Storm Dunlop’s Practical Astronomy.

MESSAGE OF THE MONTH He’s the King of the castle My lifelong interest in astronomy began in early childhood thanks to Patrick Moore and the early Apollo space missions. I made my first telescope when I was 16 and later designed and built a 6-inch Maksutov telescope, which I still have today. Recently, I was inspired by the series in BBC Sky at Night Magazine detailing how to build an observatory and I decided to design and build my own version, which turned out to be a silo-shaped unit. I believe the design requires minimal carpentry skill to build and being conical, it is easy to bend flat sheets to fit. The observatory’s vertical sides provide a very

useable space inside, with good headroom through the whole of the dome’s 2.4m diameter. I have equipped the observatory with a Meade LX90 12-inch scope, but the space would allow for a much larger instrument, and I have had up to eight people inside the observatory when a group from my local astronomy group visited a few months ago. Derek King, St Austell, Cornwall

Your observatory’s simple construction is striking, Derek. If any readers would like to get in touch with Derek for more details, do contact us for details. – Ed

Our How to articles are there to inspire – as Derek’s custom build shows, it can pay dividends to go off plan

skyatnightmagazine.com 2013

LETTERS NOVEMBER 23

GOODBYE KEITH

debate Have your say at http://twitter.com/ skyatnightmag @skyatnightmag asked: If you could travel anywhere in the Solar System where would it be? @jasonmccann0 I would love to stand on the Moon and look back at home.

I simply had to write to you to say how much I have enjoyed reading Keith Hopcroft’s column over the years and am sad to have read his final one. His wry sense of humour and his ability to poke fun in such a mischievous way at our wonderful hobby has often made me shout “I do that!” out loud. I will miss his trials and tribulations – but will of course continue with my own. Please pass on my thanks together with very best wishes for the future. Chris Hook, Mansfield and Sutton Astronomical Society After six years and 63 columns, Keith felt that he was not so much of a beginner any more; indeed, he was becoming less lost in space. Plans are developing for a new column, so stay tuned! – Ed

@AndyWin1 Pluto – so I could decide once and for all if it should qualify as a planet! @franticsmurf Saturn. My first ‘wow’ sight through the telescope. It would be humbling to look back on Earth. @willbowden I’d stay here on Exmoor, you can see most of the Solar System from here and you can still get decent cider. @Ewan_Bryce It would have to be a trip to the subsurface ocean of Jupiter’s moon Europa. What awaits in the watery depths? @jcousins1968 I would like to visit Eris and look back towards the Sun, seeing it against the rest of stars! @MikeStewart75 Pluto, to watch New Horizons fly past in 2015.

Keith’s quest for product placement only had one logical conclusion

Ron’s impressive meteor shot, captured with a 36-inch telephoto lens and signed by Sir Patrick himself

A generous man One of the few things I was good at in school was science: in 1957, I came top of the class and won a book called The Boy’s Book of Space written by Patrick Moore. It was a good read and got me thinking about the origins of the Universe. Some 10 years later I happened to be reading another book by Patrick when I noticed a picture showing a meteor photographed by an American astronomer. Patrick had written that no British astronomer had ever captured a similar shot. “Oh yes they have,” I thought. A few years earlier I had been working for the Wray Optical Company, producing telephoto lenses, and had built myself a 36-inch lens, which I fitted to my old Pentax camera. One chilly evening I set it up on a tripod in the garden to experiment with time exposures. I went inside to get another lens and on my return I witnessed a superb meteor

shower. Thinking I had missed them all, I took the film indoors and developed it. To my joy there was a lovely black streak on the negative. So, on returning home from mid-Wales, I printed off a copy of this photo and posted it to Patrick. To my amazement, he replied within days, saying, “What a superb picture, if we were doing a Sky at Night programme on meteors, we could certainly like to use it.” He had also sent a postal order to cover the cost of the photo. I returned it to him, with thanks for all the pleasure I got from reading his books. I met Patrick some years later and asked him if he would kindly sign a copy of the photo. This he did, and in his usual haste, he smudged it when he gave it back to me! Ron Payne, Croydon

What a wonderful story, Ron. I can picture your excitement as you developed the picture to reveal the impressive meteor streak. – Ed

Best direction? Next year we will be selling our house and buying a bungalow. I am also buying a large telescope. Would the back garden of the bungalow be better facing southeast, south or southwest? C J Gardner, Dumfries

Any of these will be good for general observing. If you are lucky enough to have a choice, opt for southeast: you’ll then have a good view of the ecliptic (the path of the planets) in the early evening during winter. Nearby streetlights and obstructions on the local horizon are also factors to consider. – Ed > skyatnightmagazine.com 2013

JEFF PARKER

The big

My first look at October’s BBC Sky at Night Magazine was a slow scan before I got down to article reading, picture examining and a jealous look at the reviews of equipment I might one day be able to afford. The column I always turn to after this is Keith Hopcroft’s Lost in Space, because nine times out of 10 he’d be saying how I was feeling about my own novice astro-efforts. His words made me smile... or they did until today, when I found out this issue was his last contribution. I don’t know why he’s not coming back, but I wanted you to know that he’ll be sorely missed. Samantha Walden-Jones, via email

24 LETTERS NOVEMBER

Twinkle, twinkle

The big debate @Naren_Prasad The ring systems of Saturn. Oh to be among a billion glittering blocks of ice as they tumble along a silent highway... @Kirkos73 I would sit on Enceladus and look up at the beauty of Saturn. It would be amazing!! @j_utd Halley’s Comet, that way I would get to travel around. @DavidBflower I would go to Jupiter’s moon Io. To see the volcanoes and Jupiter in the sky would be spellbinding.

I am an American who has followed and enjoyed BBC Sky at Night Magazine since its first issue. Having never seen the TV show, I must say I was thrilled at the quality and humour of each entertaining and informative programme (although I admit to a little trouble with the accents at first). I always look forward to each issue (and show), please keep up the good work. Here is a poem that I hope you find interesting. THE STAR I saw a star yellow Up high in the sky But later and lower I could not deny The same star seemed green Then white, orange and red And in moments of blue Left me shaking my head

@Sven_dog I would go to Europa and look beneath its surface. @PhilipJennings1 The Moon, to look back and see the Earth. Lots to see and do there while I’m about it! @h2thepizzo Venus, I’d live for three seconds but it would be totally worth it. @marktissington I’d go to Enceladus to see a geyser I know...

skyatnightmagazine.com 2013

EDITORIAL Editor Chris Bramley Production Editor Kev Lochun Online Editor Kieron Allen Staff Writer Elizabeth Pearson Reviews Editor Paul Money ART AND PICTURES Art Editor Steve Marsh Art Assistant Emma Brown Picture Research Sarah Kennett CONTRIBUTORS Paul Abel, Mark Bowyer, Jamie Carter, Stuart Clark, Heather Couper, Adam Crute, Lewis Dartnell, Glenn Dawes, Will Gater, Nicky Guttridge, Brian Jones, Carol Lakomiak, Pete Lawrence, Chris Lintott, Katia Moskvitch, Hazel Muir, Steve Richards, Steve Sayers, Paul Sutherland, Stephen Tonkin, David Utting, Vincent Whiteman, Paul Wootton ADVERTISING SALES Advertising Director Caroline Herbert Advertising Managers Steve Grigg (0117 314 8365), Tony Robinson (0117 314 8811) Inserts Laurence Robertson (00 353 87 690 2208)

Thanks for writing, Rick. Poor seeing low to the horizon has left me vexed on many an occasion too! – Ed

PRODUCTION Production Director Sarah Powell Production Manager Derrick Andrews Ad Services Manager Paul Thornton Ad Co-ordinator Emily Thorne Ad Designers Cee Pike, Andrew Hobson Reprographics Tony Hunt, Chris Sutch

Really the first?

LICENSING Head of Licensing and Syndication Joanna Marshall

Rick Hall, Oklahoma, US

Reading the story ‘Voyager 1 reaches interstellar space’ on www.skyatnightmagazine.com, this sentence stood out: “...on 25 August 2012, after travelling a mind-boggling 19 billion km, the probe became the first man-made object to reach the edge of our Sun’s influence”. I was under the impression that this title went to Pioneer 10, which I believe left the Solar System on 13 June 1983. Nigel Smith, via email

@BassmanBowman The very edge, gotta know what’s there!

BBC Sky at Night Magazine is published by Immediate Media Company Bristol Limited under licence from BBC Worldwide.

In 1983, Pioneer 10, pictured left, had crossed the orbit of what was at that time the outermost planet in the Solar System – Neptune. This was how the edge of the Solar System was then defined. Today, Voyager may have reached interstellar space, but it is yet to leave the Solar System. Astronomers theorise that it still has to travel through the Oort cloud, an immense collection of rock and ice held in place by the Sun’s gravity, which could stretch a quarter of the way to our nearest star, Proxima Centauri. As our knowledge of the outer reaches of the Solar System expands, so does its size! – Ed

MARKETING Head of Circulation Rob Brock Head of Marketing Jacky Perales-Morris Marketing Executive Chris Day Head of Press and PR Carolyn Wray (0117 314 8812) PUBLISHING Publisher Jemima Ransome Managing Director Andy Marshall MANAGEMENT Chairman Stephen Alexander Deputy Chairman Peter Phippen CEO Tom Bureau BBC WORLDWIDE, UK PUBLISHING Director of Publishing Nicholas Brett Head of Publishing Chris Kerwin Head of Editorial Jenny Potter Publishing Coordinator Eva Abramik EDITORIAL ADVISORY BOARD Deborah Cohen, Andrew Cohen, Jane Fletcher, Julian Hector, John Lynch

SUBSCRIPTION RATES Annual subscription rates (inc P&P): UK cheque/credit card £57; Europe & Eire Airmail £69; rest of world airmail £79. To order, call 0844 844 0260

© Immediate Media Company Bristol Limited 2013 ISSN 1745-9869 All rights reserved. No part of BBC Sky at Night Magazine may be reproduced in any form or by means either wholly or in part, without prior written permission of the publisher. Not to be re-sold, lent or hired out or otherwise disposed of by way of trade at more than the recommended retail price (subject to VAT in the Republic of Ireland) or in mutilated condition.

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......................................................................................... OOPS! s�/N�PAGE��OF�THE�3EPTEMBER��ISSUE � Maggie Aderin-Pocock is quoted as saying objects in low-Earth orbit complete an orbit of Earth once every 90 seconds. In low-Earth orbit, it takes around 90 minutes to orbit the planet.

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28

Hotshots

This month’s pick of your very best astrophotos

PHOTO OF THE

S Solar Eclipse

MONTH

PATRICK AND JOANNE POITEVIN, REPUBLIC OF KIRIBATI, 10 MAY 2013 Patrick and Joanne say: “We travelled to the Pacific island of northern Tarawa in Kiribati to witness the annular solar eclipse on 10 May 2013. The weather conditions were excellent and overall we missed only 10 minutes of coverage between first and fifth contact due to some clouds. We were the only tourists on the desolate island – truly paradise! Not bad for our 41st solar eclipse.”

Equipment: Imaging Source DMK 41 CCD camera, Lunt 35mm hydrogen-alpha solar telescope, EQ2 mount. BBC Sky at Night Magazine says: “It takes great skill to capture such a precise, symmetrical image of a solar eclipse. Patrick and Joanne have expertly positioned their equipment to record this split-second event.”

About Patrick and Joanne: “I [Patrick] have been chasing solar eclipses since the 70s. So far, I have witnessed 41 solar eclipses of which 19 were total. Joanne and I started solar imaging for last year’s Transit of Venus. We’re planning to travel to Uganda for the total solar eclipse on 3 November.”

W Super Moon PREMJITH NARAYANAN BAHRAIN 23 JUNE 2013 Premjith says: “The most important part of this photo is the inclusion of the great Tree of Life, which has survived the harsh conditions of the desert for over 400 years without water. Bahraini citizens are very proud of the landmark and it has become a popular tourist attraction.” Equipment: Canon EOS 5D Mk III DSLR camera.

skyatnightmagazine.com 2013

HOTSHOTS NOVEMBER 29

W A Persied, the Milky Way and a thunderstorm CHRISTOPH MALIN, AUSTRIAN ALPS, AUGUST 2013 Christoph says: “This image captures a thunderstorm, the Milky Way and a Perseid meteor from an alpine meadow. In the backdrop some famous Tyrol peaks are visible.” Equipment: Canon EOS 6D DSLR camera.

T The Lagoon Nebula, Trifid Nebula, M21 and NGC 6559

S Sunspot

TERRY HANCOCK, MICHIGAN, US 25 AND 29 JULY, 2 AND 4 AUGUST 2013

STUART GREEN, PRESTON, 7 JULY 2013

Terry says: “This image was captured from my backyard observatory in Michigan over the course of four nights. I am particularly pleased with the final result as these objects are only just over 20º above the horizon at best, so they are challenging targets to capture from my latitude.”

Stuart says: “For me, this image beautifully presents the fiery glow and turmoil found around sunspots, which can only be imaged in hydrogen-alpha. It’s truly one of nature’s most mesmerising spectacles and it exemplifies our Sun’s dynamic character.”

Equipment: QHYCCD QHY11 monochrome cooled CCD camera, TMB 92SS refractor, Paramount GT-1100S German equatorial mount.

Equipment: Imaging Source DMK41 monochrome CCD camera, 6-inch solar scope.

skyatnightmagazine.com 2013

30 HOTSHOTS NOVEMBER

T The Moon APRILL HARPER, BEDFORDSHIRE, 29 JULY 2013 Aprill says: “I captured this image at about 5am, before sunrise – it was at sunrise that I realised I had the ISO setting set to 2500, which is why there is no blue sky!” Equipment: 3AMSUNG�.8�CAMERA �3KY 7ATCHER� INCH�$OBSONIAN

S The Summer Triangle MIGUEL CLARO, PORTUGAL, 16 JUNE 2013 Miguel says: “In this view captured in Monte Bravo, Mourão, you can appreciate the great Milky Way alongside the well-known Summer Triangle asterism.” Equipment: Canon EOS 60Da DSLR camera, Vixen Polarie mount.

The Elephant’s Trunk Nebula X IAN RUSSELL OXFORDSHIRE �*5,9�� Ian says: “This is IC 1396, the Elephant’s Trunk Nebula in the constellation of Cepheus, captured in a narrowband image using Ha, OIII, and SII filters combined using the Hubble Palette.” Equipment: Atik 490EX CCD camera, Takahashi &31 %$8�REFRACTOR � CGEM DX mount.

ENTER TO WIN A PRIZE! WORTH

£99

skyatnightmagazine.com 2013

We’ve teamed up with the Widescreen Centre to offer the winner of next month’s best Hotshots image a fantastic prize. The winner will receive an Orion StarShoot Solar System Colour Imager IV camera, designed for capturing sharp shots of the Moon and planets. WWWWIDESCREEN CENTRECOUK�s���

Email your pictures to us at [email protected] or enter online.

COMET

The world waits for

SPECIAL

ISON Pete Lawrence looks ahead to the comet that many hope will put on the show of a lifetime

T

he past year has been charged with excitement due to the prospect of a potentially bright comet appearing in our skies during November. There have been many claims about how this visitor, officially known as C/2012 S1 ISON, could perform – ranging from it being a complete fizzle to appearing as the ‘comet of the century’, brighter even than the full Moon. What transpires as it visits the inner Solar System cannot be predicted with absolute precision. However, much like weather forecasting, as that time draws nearer the final predictions becomes less of a stab in the dark and more a statement of reality. The comet bears the name of the International Scientific Optical Network (ISON), the observing group to which its discoverers, Vitali Nevski and Artyom Novichonok, are attached. Nevski and Novichonok spotted the comet on 21 September 2012, in CCD images taken through a modest 0.4m reflector situated near the Russian city of Kislovodsk. At first they weren’t aware they had discovered a comet; that only became apparent when the find was confirmed a few days later.

C/2012 S1 ISON has the potential to be a ‘great’ comet, but they are famously fickle

At the time of discovery, the comet was mag. +18.8 and more than six times the Earth-Sun distance away. Followup observations, combined with ‘precovery’ data – information garnered from images of the comet taken up to nine months prior to its discovery by Nevski and Novichonok – allowed details of its location and motion to be accurately calculated. From this, >

DETLEV VAN RAVENSWAAY/SCIENCE PHOTO LIBRARY

A cause for hope

34

This early CCD shot of ISON was taken on 16 September through a 4-inch refractor. Hopefully you won’t need any kit to see it come perihelion

PETE LAWRENCE, ALEX CHERNEY/TERRASTRO.COM/SCIENCE PHOTO LIBRARY, SCIENCE SOURCE/SCIENCE PHOTO LIBRARY, NASA/JPL-CALTECH/UMD, NASA/SWIFT/D. BODEWITS/UMCP, NASA/JPL-CALTECH/JHUAPL/UCF, NASA/JPL-CALTECH

> astronomers were able to work out that

C/2012 S1 ISON has a near parabolic orbit. This suggests that the comet is a first-time (and one-time) visitor coming in from the Oort Cloud, a theoretical repository of perhaps trillions of comets that lies on the very outskirts of the Solar System. Early measurements showed the comet was active and this was taken as a positive sign for something impressive happening when it got closer to the Sun. Its perihelion distance was another cause for excitement: it has been predicted that C/2012 S1 ISON will pass just 1,165,000km above the Sun’s photosphere at closest approach, making it what is known as a ‘sungrazer’. Sungrazers are not uncommon – images taken by NASA’s SOHO spacecraft since 1996 have revealed an estimated 2,500 comets of this type. But many don’t make it past perihelion, either evaporating away or being ripped apart by our star’s tidal forces. A cautionary tale lies with Comet C/2011 W3 Lovejoy, which shone at around mag. – 3.0 at its brightest.

Lovejoy passed just 140,000km above the Sun’s photosphere on 16 December 2011. Its 0.5km nucleus wasn’t expected to survive perihelion, yet survive it did, and afterwards it presented a fine, straight tail. A few days later, however, it was apparent that all was not well, as the comet’s nucleus region appeared to elongate into a bar, a probable indication of a catastrophic fragmentation having occurred. It’s not known if any of the nucleus survived this event. For comparison, C/2012 S1 ISON’s nucleus is thought to be around 5km wide. The majority of Sun-skimming comets observed by SOHO are what’s known as Kreutz sungrazers. These are related

W3 Lovejoy was one, as were the Great Comet of 1843 and Comet Ikeya-Seki in 1965. However, orbital analysis of C/2012 S1 ISON reveals that it is not part of this, nor any other family of comets. There was some speculation that it might be the second member of a new group, a sibling to the Great Comet of 1680 – famed for its long tail and said have been visible in daylight after its perihelion – but the current consensus is that there is no link.

The prediction problem Astronomers calculate a comet’s light curve using a relatively simple equation with two variable factors to take its distances from Earth and the Sun into account. The distance from Earth determines the brightness via the inverse-square law: a comet appears four times brighter at half the distance, nine times brighter at a third of the distance and so on. A similar law is used for the comet’s distance from the Sun, but the multiplication factor is higher to allow for increased activity from the

“There was some speculation that ISON might be a sibling to the Great Comet of 1680”

skyatnightmagazine.com 2013

comets, thought to have fragmented from a large, unidentified parent that broke up several centuries ago. All of them share common orbital characteristics; several have put on spectacular displays. C/2011

EYES ON ISON

The story so far...

Deep Impact

Swift

The first spacecraft image of C/2012 S1 ISON was taken on 17-18 January 2013 by NASA’s Deep Impact. The comet was 793 million km from the probe at the time. A planned late-summer observing window was hampered by communication problems with the craft.

Important observations by NASA’s Swift mission at the start of 2013 were used to determine the amount of dust and water being released from the comet’s nucleus. This information was then used to make the initial estimate of the size of the comet’s nucleus to be around 5km.

Spitzer

MRO

Spitzer imaged C/2012 S1 ISON in mid-June 2013. These false-colour infrared results show a fine rocky dust tail (left) at a wavelength of 3.6+m. The 4.5+m right-hand image has had the 3.6+m result removed from it, revealing a spherical envelope of neutral gas around the nucleus.

As this issue went to print, C/2012 S1 ISON was due to make a close pass of the Red Planet. On 1 Oct it will zip by at a distance of just over 10 million km, much closer than it will ever come to Earth. It should be visible to the Mars Reconnaissance Orbiter – and, if we’re lucky, Curiosity.

C/2011 W3 Lovejoy broke apart shortly after its journey through the solar corona

One of the famed Kreutz sungrazers, Comet Ikeya-Seki was visible in daylight at its peak

nucleus. Actual observations of the comet’s brightness are then used to refine the predictions made by the equation. Using current values, the close perihelion pass of C/2012 S1 ISON is predicted to result in a brief brightness peak somewhere between magnitude –5.0 and –8.0. From discovery through to early 2013, C/2012 S1 ISON’s observed magnitudes followed predictions well. However, through spring and into the summer, the comet showed signs of a slow-down, and its observed magnitudes fell below the curve. The comet was lost in the Sun’s glare from mid-June through to late-August. When

recovered, the effects of the slow-down were obvious: the comet was dimmer than expected but was at least brightening again. At the start of November, 7th-magnitude ISON moves from Leo into Virgo, passing close to mag. +3.6 star Zavijava (Beta Virginis) on the mornings of 7-8 November. The Moon is out of the way for the first half of the month, and although the comet will be below naked-eye brightness for this period, this is a good time to try and spot it with binoculars or a small telescope. The comet is expected to become a naked-eye object around the middle of November. It has a close encounter with

mag. +1.0 star Spica (Alpha Virginis) on the 18th, the 5th-magnitude comet seeming to pass the star by less than an apparent Moon diameter. The Moon appears from this date onwards, but C/2012 S1 ISON should also be getting brighter. By the 23rd ISON starts making patterns with Mercury, Saturn and 4th-magnitude Comet 2P/ Encke. Their low position in a bright dawn sky will make this tricky to see though. The comet reaches perihelion at 18:40 UT on 28 November. That morning, the mag. –2.0 comet will probably be lost in the dawn twilight as it rises. It is expected to increase in brightness steadily > skyatnightmagazine.com 2013

36

SERPENS CAUDA

HERCULES OPHIUCHUS

CEPHEUS

DRACO

M13

d

22 Dec

29 Dec

7 Jan

CORONA BOREALIS

b

PERSEUS

Polaris

URSA MINOR

6 Dec

CASSIOPEIA

25 Jan

SCORPIUS SERPENS CAPUT

28 Nov

CAMELOPARDALIS

BOÖTES Arcturus

LIBRA

18 Feb

CANES VENATICI

Saturn Mercury 2P/Encke

COMA BERENICES

VIRGO

Capella

URSA MAJOR

LYNX

24 Nov

21 Apr

Spica Porrima

18 Nov 13 Nov

Comet C/2012 S1 ISON – Key Events

CHART BY PETE LAWRENCE, HUBLE/NASA AND ESA, ROBERT MCNAUGHT/SCIENCE PHOTO LIBRARY, GRAHAM GREEN

15 Oct 23 Oct 7 Nov 13 Nov 18 Nov 24 Nov 28 Nov 6 Dec 22 Dec 29 Dec 7 Jan 25 Jan 18 Feb 21 Apr

Regulus, Mars and the comet form a line CORVUS Approaching visual limit of binoculars (brightening) Near Zavijava Near Porrima, approaching naked eye limit (brightening) Very close to Spica Close to comet 2P/Encke, Mercury and Saturn Perihelion occurs at 18:40 UT, peak brightness reached Near to Delta Ophiuchi Just 5º from M13 Near Eta Draconis, approaching naked eye limit (dimming) Near Polaris Approaching visual limit of binoculars (dimming) Approaching visual limit of small telescopes (dimming) CENTAURUS Approaching visual limit of larger amateur scopes (dimming)

AURIGA

LEO CANCER

GEMINI

Zavijava 7 Nov

23 Oct

Regulus

skyatnightmagazine.com 2013

TAURUS

Pollux Mars

15 Oct

M44 Jupiter (Nov)

CRATER

Procyon

HYDRA

Alphard

CANIS MINOR

Betelgeuse

> throughout the day, reaching a predicted

IS THIS THE COMET OF THE CENTURY? A close first time encounter with the Sun could result in many different scenarios playing out for this comet – predicting what will happen with great accuracy isn’t currently possible. Our best guess is that C/2012 S1 ISON will slightly underperform as it approaches perihelion. Its visibility won’t be helped by the bright Moon and dawn twilight at the end of the month, and this may create an initial air of disappointment. The prospect of experienced observers picking it up in daylight on the day of perihelion will help to re-ignite excitement. As it reappears in both the morning and evening skies post-perihelion, its tail will probably become the focus of attention. It certainly has the potential to become the Great Comet of 2013, but whether it makes Comet of the Century is really in the lap of the Gods.

Castor

mag. –4.0 by 12:00 UT and raising the possibility of spotting the comet close to the Sun in daylight – use extreme caution when doing any observing while the Sun is above the horizon. C/2012 S1 ISON is predicted to reach mag. –6.0 as it sets in UK skies, just before 16:00 UT. At perihelion, the comet is estimated to peak around mag. –7.7. Of course these are just predictions and there is still room for adjustment.

Should it survive the Sun...

Hubble caught the comet in April, as it passed within Jupiter’s orbit

C/2012 S1 ISON is estimated to be mag. –2.0 as it rises on the morning of 29 November. Spotting the comet’s head will be difficult because of its proximity to the Sun. However, if there’s a respectable tail, you may be able to see it a bit earlier, against a slightly darker sky. The Moon won’t interfere much at the end of the month. At mag. –1.0, the comet may also be visible after sunset on 29 November. Again the tail may be the saving grace here, an

ISON NOVEMBER 37

optical effect known as forward scattering possibly helping to boost its visibility. The daily double appearance continues into December, but its brightness is expected to fall quickly, approaching 5thmagnitude by the 12th. The Moon starts to interfere with the evening session from this date, though the morning appearance remains good, with the comet rising earlier and so managing to get higher in darker skies. On the 12th, the comet rises about four hours before the Sun. After 22 December, C/2012 S1 ISON becomes circumpolar from the UK and never sets. On Christmas night, it should be on the threshold of naked-eye visibility. It passes closest to Earth on Boxing Day, missing our planet by a comfortable 64.2 million km. The comet’s path takes it within 2.5° of Polaris on 7 January, but you’ll need binoculars to see it. Sharing the same field of view with the comet, Polaris should make a good locator. As it heads out into the Solar System, C/2012 S1 ISON passes through Camelopardalis, eventually spiralling into Auriga by the middle of 2014. By the end of February next year it’ll become a tricky visual object for small to medium telescopes. Large amateur telescopes will probably lose the comet visually by the end of March 2014. But before it disappears forever, C/2012 S1 ISON may bestow two parting gifts. Earth is predicted to pass through the

Will ISON put on a show anywhere near as impressive as C/2006 P1 McNaught did in 2007? Only time will tell

debris stream of the comet sometime around 12-15 January and there’s a low possibility of a meteor shower from it. The comet’s fine dust may also be sufficient to act as a seeding agent for high-altitude noctilucent clouds, so next year’s season could be one to watch. S

JOIN THE ISON OBSERVING CAMPAIGN If C/2012 S1 ISON puts on its best appearance it will be an impressive comet, admired and photographed by all. However, if this fails to occur, the worst case scenario still gives it the potential to be the target of some excellent scientific research. The comet has attracted the attention of amateurs and professionals alike, and so in an attempt to coordinate all observations, NASA has backed the Comet ISON Observing Campaign. The reason so much effort has been made to bring all ISON observations together is that to get a reasonably long lead time for a fairly large sungrazing comet is quite rare. Of the many sungrazers that are discovered via SOHO, the majority are destroyed soon after they are picked up. To be able to do a long-term study on an ancient piece of the Solar System coming in towards the Sun for the first time is very special indeed. The campaign is far-reaching, with observations planned from a number of

Sun-watching spacecraft as well as planetary missions such as Messenger, Venus Express and Dawn. NASA is even planning to launch a balloon-borne telescope, called BRISSON, solely to watch the comet. Of course, you too can play a part: amateurs are being encouraged to submit magnitude estimates, activity reports and images of the comet to the Comet ISON Observing Campaign, either through its Facebook group (see www.ISONcampaign.org) or by logging observations with the University of Maryland’s Amateur Observers’ Program (http://aop.astro.umd.edu). The Planetary Science Institute in Arizona is also looking for images showing the morphology (shape) of C/2012 S1 ISON’s coma as it nears Earth, from which they hope to determine the rotation of the comet’s nucleus, the behaviour of its tail near the Sun and more. Head to www.psi.edu/ ison for full details.

ABOUT THE WRITER Pete Lawrence loves the challenge of imaging transient objects like this comet. He writes The Sky Guide and appears on The Sky at Night each month.

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COMET

SPECIAL

Chirality

THE NEW SEARCH FOR LIFE IN THE SOLAR SYSTEM

THINKSTOCK, NASA/JPL, ESA 2001

A powerful new technique to look for life in our Solar System will soon be tested on a comet. Stuart Clark reports on how searching for life on planets and moons could get a lot easier

Handedness may hold the key to discovering life on nearby planets; inset: Rosetta fires its probe at a comet

A

round this time next year, something amazing will be taking place. A small European robot will be detaching from its mothership and descending onto the icy surface of a comet, the culmination of a decade-long chase through the Solar System. Launched in 2004, ESA’s Rosetta mission has spent the past 10 years synchronising its orbit with comet 67P/Churyumov-Gerasimenko – a primordial chunk of ice and rock in deep space. Rosetta’s robotic lander, called Philae, will search the comet for clues about how life began on our world. In doing this, it will pioneer a new technique that could eventually be used to make looking for life on the various planets and moons of our Solar System as easy as mapping them from orbit. One day, it may even allow space telescopes to identify living Earth-sized planets around other stars. The new method exploits the fact that life has a unique signature that differentiates it from non-living matter. It is called chirality. Biological molecules can exist in mirror-image forms, in the same way as our hands are reversed. Life on Earth uses ‘left-handed’ proteins almost exclusively (see box ‘What is chirality’, over the page).

A nose for adventure This overwhelming preference is a distinguishing feature of life. No one knows whether it came about because there were more left-handed molecules available during the formation of Earth’s first living things, or whether those early biological systems somehow just selected the left-handers. The origin of life is the ultimate mystery. No one knows the conditions in which our world went from being habitable to being inhabited. There is no laboratory experiment yet that has taken a flask of chemicals, combined them in some way, and produced life. > ABOUT THE WRITER Dr Stuart Clark is a science writer, author of The Sky’s Dark Labyrinth trilogy and winner of the 2013 European Astronomy Journalism Prize.

> A major problem is that we don’t really know what

chemicals to put in that flask or what to do with them once they are in there. Rosetta will help to answer these questions because it is the first space mission to carry an instrument capable of measuring the handedness of a molecule. The device in question is called COSAC, which stands for Cometary Sampling and Composition. “It is essentially like a nose,” says Alexandra MacDermott of the University of Houston in Texas, one of the instrument team members. The technical term for what this instrument does is gas chromatography. After anchoring itself to 67P/Churyumov-Gerasimenko, the Philae lander

will begin to search for chiral molecules. Samples of the comet’s ice will be placed into ovens and heated to turn them into a gas. The molecules in that gas will then be identified by their chemical composition and chirality, and their abundance measured. Although very few researchers would expect to find life on a comet, by detecting chiral molecules there the investigation will give us an inventory of the building blocks that were available for life’s development on the early Earth, and potentially elsewhere in the Solar System. “This is a once in a lifetime opportunity,” says Fred Goesmann of the Max Planck Institute for

ESA 2001. ILLUSTRATION BY MEDIALAB, THINKSTOCK, NASA/JPL

WHAT IS CHIRALITY? Look at your hands. Both of them are made of the same type of fingers, yet there is no way you can rotate your right hand to be identical to your left. The thumbs will always be on opposite sides of your hands, or upside down if you turn one over. This is why we have to put the correct hand into the correct glove – and the correct foot into the correct shoe. This property of mirror images is known as chirality or handedness and molecules can be chiral too. Instead of fingers, atoms are the distinguishing feature. Although chemistry produces equal numbers of left- and right-handed molecules, life uses only left-handed building blocks, called amino acids,

skyatnightmagazine.com 2013

for its proteins. No one knows how this preference came about. One possibility is that right-hand amino acids were more easily destroyed by interactions with naturally occurring states of ultraviolet light than left-handed ones. Other hypotheses have been suggested as well, but as yet there is no clear favourite. One thing is certain: a mixture of right- and left-handed amino acids cannot make workable proteins. This is because proteins rely on folding themselves into a specific shape, and these shapes are determined by the handedness of the individual amino acids.

The Philae lander will bake samples of a comet to reveal its secrets

Like your hands, the proteins essential for life show chirality

SEARCH FOR LIFE NOVEMBER 43

Solar System Research in Germany, the instrument’s principal investigator.

A successor awaits The potential of chiral discrimination is so great that, even before COSAC has returned its results, astrobiologists are working on a newer version of the instrument called MOMA (see box ‘Life on Mars’, overleaf). MOMA will be part of the ExoMars rover, ESA’s upcoming mission to the Martian surface. In addition to gas chromatography, it will also laser its samples to investigate heavier molecules that cannot simply be baked out of the soil. This time it will be looking not for the precursors of life, but for evidence that life once existed on the Red Planet. “It wouldn’t be too strange to think that a long time ago bacterial life could have been possible on Mars,” says Goesmann, who is also MOMA’s principal investigator. The question of life on Mars is a perennial favourite but, perhaps surprisingly, no mission

“Detecting chiral molecules on a comet will give us an inventory of the building blocks available for life”

has looked for life since the Viking spacecraft of the 1970s. The most recent NASA rovers, such as Curiosity, have concentrated on determining whether Mars could have been habitable. This is because for many years the interpretation of the Viking data was that not even a hint of life had been found. Now, however, there have been a number of scientists who wonder whether that interpretation was too conservative. The first run of Viking’s Labeled Release life detection experiment gave a promising signal that microbes were present in the Martian sample scooped from the ground. Repeated runs failed to reproduce the signal and so the conclusion was that no life had been discovered. Recently, however, a new interpretation has been discussed that involves the presence of carbonbased (organic) molecules. Goesmann finds the argument quite persuasive, although he is determined to keep an open mind. “Quite often in these research fields we go to places with an expectation of what we will find and then nature tells you, ‘no, you were wrong’,” he says. So he is happy to wait for MOMA to tell him what is at the ExoMars landing site, rather than speculate. As great as it will be to have MOMA on the surface of Mars, if the evidence of previous life is only sparsely distributed across the planet’s surface, the chances of the instrument being in the right place are small. An army of rovers would be needed in order to make detection likely. Ideally there >

Data from the Viking landers suggested there could be microbes on Mars, but the results were later discounted

skyatnightmagazine.com 2013

44

Data processing unit

Laser pump source and electronics

LIFE ON MARS? Vacuum pump

ESA X 2, MAX PLANCK INSTITUTE FOR SOLAR SYSTEM RESEARCH, THINKSTOCK, PROFESSOR CHARLES COCKELL

ESA’s ExoMars is a bold mission designed to search Mars for biological signals. In 2016, the Trace Gas Orbiter will map the planet to look for the cause of the methane gas that occasionally appears in the atmosphere. On Earth, most of the methane comes from living creatures: only a small percentage comes from geological processes. Then, in 2018, the ExoMars rover, containing the Mars Organics Molecule Analyser (MOMA) will be sent on its way. Should all go well with the touchdown in 2018, MOMA will become the first astrobiology payload on Mars since the Viking landers of the late 1970s. In the four decades since those NASA missions technology has moved on greatly,

Gas chromatograph will analyse heated samples for chirality

Laser head will pulse heatresistant samples

Tapping station Oven

Radio-frequency electronics Sample carousel

Sample tray

MOMA’s complex assembly means it will be the largest instrument in the ExoMars rover

> would be an instrument that could detect

chirality from orbit, making the search for life as easy as mapping the celestial body. And that dream is exactly what William Sparks of the Space Telescope Science Institute and his colleagues are studying. Way back in 1848, the 26-year-old Louis Pasteur discovered that chiral molecules imprinted a detectable signature on light. Following an interaction with a chiral molecule, the light began to twist in a way that is invisible to our eyes but detectable with certain crystals. The twisting is called circular polarisation, and can be detected with special instruments. skyatnightmagazine.com 2013

Mass spectrometer will determine chemical structure of samples

although the techniques remain essentially the same. Martian soil will be heated in miniature ovens and the gas driven off analysed. Because the technology to clean the ovens

does not yet exist, each one can only be used once. For Viking, they had just three. MOMA has closer to 30, the exact number depending on the final design. Additionally MOMA will have the capacity to detect chiral signatures, a fingerprint of biological molecules.

Sparks and colleagues have been testing components for a spacecraft instrument suitable for a Mars orbiter to look for the circular polarisation that would betray chiral molecules. “The concept has been validated in the lab. The next step is to build a complete instrument,” says Sparks. To that end, he and his colleagues, in particular James Hough, University of Hertfordshire, a world expert on polarimetry, are intensively studying ways to do this. It would be sufficiently compact to fly on a small CubeSat to Earth orbit for testing. Even if the opportunity to fly a test mission does not materialise, a test instrument could be used on a balloon or an aircraft to improve the interpretation of the signals.

ESA’s ExoMars rover will use similar techniques to the Viking landers, but much better technology

SEARCH FOR LIFE NOVEMBER 45

One day it may be possible to scour planets around other stars for chiral molecules

This will be essential because light bouncing off minerals and dust particles can also cause a circular polarisation signal. If you are not careful, these could give a ‘false positive’, a signal that is interpreted as a chiral molecule but in reality is just a lump of inanimate rock. “The good news is that all the work we have done so far shows that we are not swamped by false positives,” says Sparks. Nevertheless, he would be wary of declaring a detection of life on Mars just from a chiral signal: “With our current state of knowledge, that would be a place that we look at more closely, rather than a place we would say definitely has life.” Such an instrument could survey any celestial body it can be placed into orbit around. But that’s not all: by hooking it up to a space telescope it could even be used to survey planets around other stars.

Interstellar travel insurance

“In 1848, Louis Pasteur found that chiral molecules imprinted a detectable signature on light”

MacDermott has been studying such polarimeters for future space telescopes, or even for giant ground-based telescopes. “You would need the planet to have a widespread biosphere such as Earth’s to get a detectable signal,” she cautions. Although sending missions into space is expensive, there is a practical reason that MacDermott can see as well. “Interstellar travel may never be possible, so a way of looking for life on distant planets, using something on or near Earth, would be a very nice thing to have,” she says. Although such an instrument is decades into the future, this time next year Rosetta’s Philae lander will be drifting down to the surface of comet 67P/ Churyumov-Gerasimenko. When it anchors itself in place and begins to sift the primordial ice for signs of chiral molecules, a new chapter in the search for extraterrestrial life will have begun. S

THE EXPERT Charles Cockell, professor of astrobiology at the University of Edinburgh, explains why now is one of the most exciting times to be looking for life elsewhere in the Universe What’s driving the current explosion of astrobiology missions? We have crossed a threshold where technology now allows us to go and investigate. We have found environments that are a lot more habitable than people might have thought: liquid water beneath the surface of Europa, water in the plumes of Enceladus. Now there is even discussion of clays and ice on Ceres. With potentially habitable conditions in some quite surprising places, the search for life elsewhere has gathered pace. How do we go about searching for life? The first thing we would be looking for are

environments that could potentially support life, but that may not imply the presence of life at all. If you find an environment that can support life but there is no life there, that’s just as interesting because it tells you something about the distribution of life in the Universe: that it must be localised, in particular places. So the first priority is to search for habitable conditions. How important are chiral molecules in the search for life? Chirality is something that life tends to do because if you are building up a complex biochemistry you want molecules to be compatible with each other. So looking for chirality is certainly a good way to hunt for life, but I don’t think it is necessary for molecules to be chiral at the beginning for life to originate.

What does looking for life elsewhere tell us about life on Earth? It tells us about whether the origin of life is inevitable, and it also tells us that once life occurs, whether it is inevitable that it will colonise a whole planet and create a large biomass. At the moment we just don’t know whether the origin of life is inevitable. Once you have conditions that are suitable for it, is it a strange chemical quirk that is extremely unlikely, or does it always occur? What’s the most exciting thing happening in astrobiology at the moment? I think the search for exoplanets is pretty exciting. Finding Earth-like planets will give us a better idea of how common these worlds are in the Universe and whether they could harbour life.

skyatnightmagazine.com 2013


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THE SKY GUIDE NOVEMBER 47

The Sky Guide

November Close encounters of the cometary kind

All the theories and predictions about what comet C/2012 S1 ISON will do when it approaches the Sun will meet with reality this month, as the comet reaches perihelion on 28 November. Will it survive? Only time will tell.

PETE LAWRENCE

OUR STARGAZING EXPERTS PETE LAWRENCE As well as writing The Sky Guide, Pete can be seen on BBC’s The Sky at Night. On page 60, he offers advice on imaging C/2012 S1 ISON in the run up to its close pass with the Sun.

STEVE RICHARDS Steve is passionate about observing deep space and likes nothing more than taking images of distant galaxies – follow his Deep-sky tour on page 56 to find a host of fascinating objects.

STEPHEN TONKIN When he’s not doing astronomical outreach of one form or another, Stephen heads to the New Forest to observe the night sky. Take his Binocular tour on page 58. skyatnightmagazine.com 2013

48

HIGHLIGHTS Your guide to the night sky this month This icon indicates a good photo opportunity

1

FRIDAY Comet C/2012 S1 ISON is predicted to be around 8th magnitude at the moment. This morning it lies just over 2º to the west of mag. +4.0 star Sigma (m) Leonis. The waning crescent Moon (6% lit) is just below mag. +3.0 Porrima (Gamma (a) Virginis) this morning.

2

SATURDAY Minor planet 4 Vesta is very close to mag. +4.1 star Nu (i) Virginis in this morning’s sky. See page 51. From tonight until from 10th is a good time to take this month’s Deepsky tour – see page 56. You can also head out later in the month, between the 24th and the 30th.

4

MONDAY The Moon appears as an incredibly thin waxing crescent (1% lit) this evening – look low in the southwest immediately after sunset.

6

WEDNESDAY The waxing crescent Moon (13% lit) lies about 8º northwest of mag. –4.3 Venus in the twilight following sunset this evening. Look low in the south-southwest around 17:00 UT. Tomorrow evening the crescent Moon (22% lit) lies 12º northeast of Venus.

7

8

13

17

W FRIDAY The fabulous Andromeda Galaxy, M31, is close to overhead at around 21:30 UT. If you can spot it, the light you’re seeing left the galaxy around 2.5 million years ago.

THURSDAY Comet C/2012 S1 ISON lies 1º from mag. +3.6 star Zavijava (Beta (`) Virginis) this morning. The comet should be around 7th magnitude at this time, so you’ll need binoculars to pick it up.

WEDNESDAY If it follows predictions, comet C/2012 S1 ISON should be just on the threshold of naked-eye visibility and around 3º south (that’s down and right as seen from the UK) of the mag. +2.7 binary star Porrima (Gamma (a) Virginis).

SUNDAY The annual Leonid meteor shower peaks tonight with a zenithal hourly rate of 10 meteors per hour. The full Moon will interfere very badly with this year’s display.

18

MONDAY Comet C/2012 S1 ISON lies very close to the mag. +1.0 star Spica (Alpha (_) Virginis) in the dawn twilight sky. The close pass is visible low in the southeast from around 05:15 UT until the sky gets too bright, probably around an hour later.

PETE LAWRENCE X 6

24

SUNDAY Fifthmagnitude comet 2P/Encke and third-magnitude C/2012 S1 ISON will be 2º apart this morning, visible low in the southeast. An equilateral triangle formed by Mercury, Saturn and mag. +2.8 star Zubenelgenubi (Alpha (_) Librae) points towards the comets.

skyatnightmagazine.com 2013

21

22

27

28

W THURSDAY Mag. –2.4 Jupiter is approximately 5.5º above the Moon around midnight. At this time, mag. +3.6 star Lambda (h) Geminorum can be seen just below the Moon too. It’s occulted shortly after midnight, reappearing approximately an hour later.

26

TUESDAY Mag. –0.6 Mercury and mag. +0.8 Saturn are just 25 arcminutes apart in this morning’s sky. Catch the pair low in the southeast just before sunrise; look from 06:30 UT onwards.

WEDNESDAY Mag. +1.3 Mars lies 7º to the southwest of the waning crescent Moon (36% lit) in the early hours.

FRIDAY Things are starting to get crowded low in the east-southeast as dawn breaks. Fourthmagnitude comet C/2012 S1 ISON, mag. –0.6 Mercury, mag. +0.8 Saturn and 5th-magnitude comet 2P/Encke form a tight diamond pattern. See page 50.

THURSDAY Comet C/2012 S1 ISON reaches perihelion, the point in its orbit where it passes closest to the Sun. This is a critical time for the comet and represents the period when it will be at its brightest. From the UK, the encounter takes place with the Sun below the horizon.

THE SKY GUIDE NOVEMBER 49

What the team will be observing in November Pete Lawrence “This is the make or break month for comet C/2012 S1 ISON as it plunges towards its close call meeting with the Sun. This will be an exciting time for me and I’ll be ready with my camera!” Paul Money “I’ll be watching and imaging the lunar occultation of Lambda Geminorum on the morning of the 22nd, just after midnight. Occultations are fascinating as they show the clockwork precision of the Solar System in action.” Steve Marsh “I’ll be taking advantage of Jupiter’s two photographic opportunities this month, one at high magnification and the other a wider encounter with the waning Moon.”

12

TUESDAY The peak of the Northern Taurid meteor shower occurs tonight, the shower having a zenithal hourly rate of seven meteors per hour. A bright waxing gibbous Moon (77% lit) will interfere until moonset at around 02:30 UT.

Terms you need to know UNIVERSAL TIME (UT) Events are given in Universal Time (UT), the standard time used by astronomers worldwide. UT is the same as GMT. RA (RIGHT ASCENSION) AND DEC. (DECLINATION) These coordinates are the night sky’s equivalent of longitude and latitude, describing where an object lies on the celestial ‘globe’.

Icons explained

How to tell what equipment you’ll need NAKED EYE Allow 20 minutes to become dark-adapted

23

SATURDAY X The waning gibbous Moon (67% lit) occults open cluster M67 in Cancer. Keep an eye on the Moon as soon as it pops above the horizon just before 22:00 UT. The cluster’s faint stars will be easier to see as they reappear from behind the Moon’s dark edge, just before 23:00 UT.

BINOCULARS 10x50 recommended

PHOTO OPPORTUNITY Use a CCD, webcam or standard DSLR SMALL SCOPE Reflector/SCT under 150mm, refractor under 100mm

29

W FRIDAY Our first chance to see whether C/2012 S1 ISON has survived its perihelion passage and how this has affected the development of its tail. The comet will be a tricky twilight object visible both in the morning and evening sky – see page 50.

LARGE SCOPE Reflector/SCT over 150mm, refractor over 100mm

Getting started in astronomy If you’re new to astronomy, you’ll find two essential reads on our website. Visit http:// bit.ly/10_Lessons for our 10-step guide to getting started and http://bit.ly/First_Tel for advice on choosing your first scope.

skyatnightmagazine.com 2013

50

Looking low towards the south-southeast on 18 November at 05:40 UT

DON’T MISS... 3 TOP SIGHTS

Looking low towards the south-southeast on 22 November at 06:40 UT

Mercury Spica

Saturn

C/2012 S1 ISON

A double helping of naked-eye comets

2P/Encke 5º 0.5º

WHEN: All month; the Moon starts to interfere from the 18th

C/2012 S1 ISON will pass several familiar sights on its way to the Sun

ALL EYES WILL be watching comet C/2012 S1 ISON during November. It should brighten as it moves in towards the Sun, becoming a naked-eye object by the middle of the month, although it’ll also be contending with the dawn twilight and a bright Moon at this time. A more predictable comet known as 2P/Encke will be sharing the early morning sky with ISON and may itself be spotted with the naked eye.

1 November can also be used to locate minor planet 4 Vesta and dwarf planet Ceres (see opposite page). Comet C/2012 S1 ISON should have brightened to around 7th magnitude on the mornings of 7-8 November and be close to mag. +3.6 star Zavijava (Beta (`) Virginis). Mag. +3.9 Zaniah (Eta (d) Virginis) is the next prominent star for a visit, C/2012 S1 ISON passing 1.5º south of it on the

2P/Encke has the shortest known period of any comet at just 3.3 years. The start of November has an 8th-magnitude C/2012 S1 ISON among the rear paws of Leo. With the Moon out of the way, this is a great time to look for it with a small telescope or good binoculars. Comet 2P/Encke should be marginally brighter, lying 20º away in the Bowl of Virgo. A line drawn between ISON and Encke on

1 Nov

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C/2012 S1 ISON catches up with (then races past) 2P/Encke over the month, as it heads to perihelion on the 28th

skyatnightmagazine.com 2013

11th. On this date, 2P/Encke should be on the verge of naked-eye visibility at mag. +5.6. Find it approximately two-thirds of the way along a line joining mag. +1.0 star Spica (Alpha (_) Virginis) and mag. +3.4 star Heze (Zeta (c) Virginis). The next big meeting occurs on the morning of the 18th. The full Moon will be big, bright and up all night by then, so it will interfere from this date. Mag. +5.0 C/2012 S1 ISON will be less than 1º from Spica, while mag. +4.7 2P/Encke will be around 1.5º from Mercury. By 20 November both comets should be of similar brightness at around mag. +4.5. With perihelion just a week away, C/2012 S1 ISON’s pace towards the Sun appears to pick up and it overtakes 2P/ Encke on the 24th. Mag. +2.9 ISON will be less than 2º from mag. +4.9 Encke on this date. Both comets will be close to Mercury and Saturn at this time but they will also be challenged by low altitude as dawn approaches. C/2012 SI ISON finally reaches perihelion at 18:40 UT on 28 November. You can read more about its prospects and visibility in full in our feature article on page 33.

!

NEED TO KNOW

2P/Encke is periodic, meaning it makes regular orbits around the Sun. C/2012 S1 ISON is non-periodic – this will be its only visit.

THE SKY GUIDE NOVEMBER 51

Vesta and Ceres WHEN: First week of November, 04:00 UT to 05:00 UT

MINOR PLANET 4 Vesta can appear brighter than all the other main asteroids and dwarf planets, sometimes becoming bright enough to be seen with the naked eye. Unfortunately that’s not going to happen this month, but at around 8th magnitude it will be within the reach of a pair of binoculars or a small telescope. It’s located in the rather busy region of sky occupied by comets C/2012 S1 ISON and 2P/Encke. Vesta passes very close to the slightly variable star Nu (i) Virginis at the start of the month, missing the star by around 0.5 arcminutes during the early afternoon of 2 November. The asteroid can still be seen around 0.25º from the star on the mornings before and after closest approach.

Vesta being around mag. +8.0 and Ceres closer to mag. +9.0, a wide-field shot should record all four objects without too much trouble.

rather unique shot as the line between comets C/2012 S1 ISON and 2P/ Encke has Vesta and Ceres located along it. With both comets being around 7th magnitude,

A thin waning crescent (6% lit) Moon lies close to mag. +3.4 star Porrima (Gamma (a) Virginis) on the morning of 1 November and an even thinner Moon (1% lit) occults mag. +1.0 star Spica (Alpha (_) Virginis) on the morning of the 2nd. This is good news if you’re trying to locate Vesta as it means the Moon won’t really interfere, and creates a lovely observing diversion as dawn approaches. The asteroid moves into the Bowl of Virgo throughout the rest of the month. C/2012 S1 ISON overtakes Vesta to the south during the first week of November, while dwarf planet Ceres keeps track with Vesta slightly farther to the north. If you’re an astro imager, a wide-field shot of the region on 1 November may yield a

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15 Nov

1 Nov

Vesta and Ceres occupy Virgo’s bowl, with the comets close early on

Saturn and Mercury – a close conjunction WHEN: 23-30 November, from 06:45 (centre of the UK) 21 Nov 22 Nov 23 Nov

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24 Nov

Mercury 25 Nov

Saturn

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26 Nov

_ 26 Nov

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27 Nov 28 Nov 29 Nov 30 Nov

The Orionids peak on 21 October, but you’ll haveSE to contend with a bright Moon The two planets are at their closest on the 26th, just 25 arcseconds apart

THERE’S NO GETTING away from the fact that you’re going to have to be an early riser during November if you want to see the main celestial action. As well as comets, a dwarf planet and an asteroid, the main planets are putting on a show too. Saturn is in conjunction with the Sun on 6 November, so will be lost in the Sun’s glare for a period around this time. However, the planet manages to reappear in the morning sky towards the end of the month. As it does so, Mercury, which has been putting on a good morning show of its own, closes in on it. By 23 November, both planets are just 3.5º apart and closing. Brighter Mercury is the object to look out for, its

location being key to finding dimmer Saturn. Mercury is mag. –0.6 on 23 November, Saturn +0.8. Both planets remain at this brightness as they close in on one another. From the UK, the closest encounter will be on the 26th when they are separated by just 25 arcminutes, which is slightly less than the apparent diameter of the Moon. Telescopically, Mercury will be showing a gibbous phase (81% lit) on this date. Saturn’s tilt is around 20º at the moment so the rings are well displayed.

!

NEED TO KNOW

The planets of the Solar System occupy similar orbital planes; it is this ‘co-planar’ nature that allows us to see conjunctions from our perspective on Earth.

skyatnightmagazine.com 2013

52

THE PLANETS Pick of the month

C/2012 S1 ISON

Spica

Spica

Mercury

Mercury

MERCURY BEST TIME IN NOVEMBER:

16 November, from 06:30 UT ALTITUDE: 6º (low, measured from centre of UK) LOCATION: Virgo DIRECTION: East-southeast

Saturn ESE

ESE 18 November 06:30 UT

13 November 06:30 UT

RECOMMENDED EQUIPMENT:

Naked eye or binoculars FEATURES OF INTEREST:

Phase (you’ll need a small telescope) FOLLOWING A POOR showing last month, Mercury is in inferior conjunction with the Sun on 1 November, when it will be lined up with our local star on the earthward side of its orbit. Obviously around this time the planet won’t actually be visible, but things do improve throughout November. Following conjunction, the Solar System’s innermost planet rapidly moves itself into a good position in the morning sky, probably becoming visible to the naked eye about 40 minutes before sunrise on 6 November. Its brightness increases over the following days from mag. +2.5 on the 6th, through to a peak of –0.6 at the end of the month. Greatest western (morning) elongation occurs on 16 November, when the mag. –0.3 planet appears separated from the Sun by a respectable 19 º. Through

LIBRA Mercury LIBRA

Saturn

Saturn

C/2012 S1 ISON

Mercury

2P/Encke

ESE

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28 November 06:30 UT

Mercury brightens throughout the month, and sees visits from the Ringed Planet and two comets

a telescope the planet will have an apparent diameter of 7 arcseconds and be showing a 52% lit phase. It’ll also rise approximately two hours before the Sun, making this an excellent viewing opportunity. On 22 November, mag. –0.6 Mercury and mag. –0.8 Saturn will be in the same general area of sky. Comet C/2012 S1 ISON will hopefully be around 3rdmagnitude at this time, passing to the south of both planets as it heads towards

perihelion on the 28th. The planet-comet meeting will occur in the bright morning twilight, which will make seeing it harder than it would be against a dark sky. By the 26th, Mercury and Saturn will be very close at just 25 arcminutes apart. By the end of the month Mercury, still mag. –0.6, rises about 90 minutes before the Sun. On 30 November, Mercury, mag. +0.8 Saturn and a waning crescent (9% lit) Moon grace the dawn sky, low down in the southeast.

How the planets will appear this month The phase, tilt and relative sizes of the planets in November. Each planet is shown with south at the top, to show what it looks like through a telescope VENUS 15 Nov

MARS 15 Nov

JUPITER 15 Nov

SATURN 15 Nov

URANUS 15 Nov

NEPTUNE 15 Nov

20” 30” 40” ARCSECONDS

50”

PETE LAWRENCE X 2

MERCURY 15 Nov

MERCURY 30 Nov 0”

skyatnightmagazine.com 2013

10”

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THE SKY GUIDE NOVEMBER 53

JUPITER BEST TIME IN NOVEMBER:

30 November, 03:00 UT ALTITUDE: 59º LOCATION: Gemini DIRECTION: South Jupiter is in Gemini, close to mag. +3.5 star Wasat (Delta (b) Geminorum). Rising around 20:30 UT at the start of the month, the planet reaches its highest point in the sky, due south, while the sky is dark. This is the time when scopes should give the best views. From the centre of the UK, Jupiter manages to climb to an impressive altitude of 59 º. A telescope will show at least two dark belts crossing its 41-arcsecond, slightly flattened disc. The Great Red Spot may also be seen nestling in the southernmost belt, although its appearance is subject to timing. A waning gibbous Moon (81% lit) lies 5.5º to the south of mag. –2.4 Jupiter on the night of 21/22 November. URANUS BEST TIME IN NOVEMBER:

1 November, 22:00 UT ALTITUDE: 40º LOCATION: Pisces DIRECTION: South Uranus was at opposition last month. The planet is currently in Pisces close to mag. +4.4 and +4.3 stars Delta (b) and Epsilon (¡) Piscium. Shining at mag. +5.8, the easiest way to locate Uranus is to use a pair of binoculars. It is visible for most of the night all month, passing through its highest point in the sky, due south, when the sky is nice and dark. NEPTUNE BEST TIME IN NOVEMBER:

1 November, 19:45 UT ALTITUDE: 26º LOCATION: Aquarius DIRECTION: South Distant Neptune is in Aquarius between mag. +4.8 star Sigma (m) and mag. +4.3 Iota (f) Aquarii.

This dim, mag. +7.9 planet requires at least a pair of binoculars to see. Visible from darkness into the early hours, Neptune is due south as the sky darkens at the end of November. VENUS BEST TIME IN NOVEMBER:

6 November, from 17:00 UT ALTITUDE: 6º (low) LOCATION: Sagittarius DIRECTION: South-southwest Venus reaches greatest eastern elongation on 1 November and is visible just after sunset, low in the south-southwest. There’s a lovely, low encounter between mag. –4.3 Venus and the thin waxing crescent Moon (13% lit) on the 6th, visible just after 17:00 UT. On the 18th and 19th, the planet is around 0.5º from mag. +2.1 star Nunki (Sigma (m) Sagittarii). MARS BEST TIME IN NOVEMBER:

30 November, 05:30 UT ALTITUDE: 35º LOCATION: Virgo DIRECTION: South-southeast Mars starts November close to the rear paws of Leo, rising just after 01:30 UT early in the month and by 01:00 UT at the end. To the naked eye it looks like a mag. +1.5 pink star; it is disappointing through a telescope as its 5-arcsecond disc doesn’t reveal much detail. SATURN BEST TIME IN NOVEMBER:

30 November, 06:30 UT ALTITUDE: 4º (low) LOCATION: Libra DIRECTION: East-southeast Saturn is in conjunction with the Sun on 6 November and can’t be seen around this time. However, the planet just starts to reappear in the morning sky by the end of the month. On the 22nd it is mag. +0.8 and can be seen low in the dawn twilight with mag. –0.6 Mercury and comet C/2012 S1 ISON.

See what the planets look like through your telescope with the field of view calculator on our website at: http://www.skyatnightmagazine.com/astronomy-tools

Jupiter’s moons Using a small scope you’ll be able to spot Jupiter’s biggest moons. Their positions change dramatically during the month, as shown on the diagram. The line by each date on the left represents midnight. JUPITER IN NOVEMBER WEST EAST

DATE

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 01 8 7 6 5 4 3 2 1 0 1 2 3 4

5 6 7 8

arcminutes

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Io

Europa

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Callisto

skyatnightmagazine.com 2013

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01 Nov 2013

04:29 UT

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56

DEEP-SKY TOUR With Steve Richards

Six of the best night-sky sights in the Hunter, the Twins and the Charioteer  �

3

Tick the box when you’ve seen each one



The Crab Nebula is all that remains of a supernova recorded in 1054

4

CHART: PETE LAWRENCE, CRAB NEBULA: THINKSTOCK

1

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M38 We start this month’s tour hunting clusters in the constellation of Auriga. The first, M38, can be found halfway along a line drawn between mag. +2.7 star Hassaleh (Iota (f) Aurigae) and mag. +2.6 star Theta (e) Aurigae. A 4-inch telescope will show in excess of 40 stars despite the rich star field that forms the cluster’s backdrop. Among the 100-plus stars within the cluster are many yellow giants, with several chains of stars becoming visible in a 6-inch telescope. Many observers describe these star chains as forming the Greek letter Pi (/), although some see them as a simple cross. � SEEN IT

M37 Our second stop is M37, the brightest of the three clusters within Auriga at mag. +5.6. This is a rich, dense cluster with a population in excess of 500 stars, a third of which shine brighter than mag. +12.5. Look for it 6° to the southeast of M38. The cluster is a wonderful sight in an 8- to 10-inch telescope, through which more than 200 stars will be visible. A 4- to 6-inch telescope will still provide a great view, revealing the bright yellow-orange star at the core of the cluster and some of the red giants scattered about it. � SEEN IT

skyatnightmagazine.com 2013

5

6

THE CRAB NEBULA Leaving Auriga and heading towards the constellation of Orion, our next port of call is the wonderful Crab Nebula, M1. A deep-sky astrophotographer’s favourite, this object is all that is left of a supernova first recorded by Chinese astronomers in 1054 – they described the supernova as shining around four times brighter than the planet Venus, which would have made it visible during the day. The nebula it left behind lies just 1º to the northwest of mag. +3.0 star Zeta (c) Tauri. A 6-inch telescope will show a faint grey patch of nebulosity against a darker background, while a 10-inch or larger instrument will reveal the elongated crab shape from which M1 gets its common name. � SEEN IT

THE MONKEY HEAD NEBULA From the Crab Nebula, look to the east towards mag. +3.3 star Propus (Eta (d) Geminorum). From Propus, shift your gaze 2.3º to the southwest and you’ll arrive at our next object, the Monkey Head Nebula. This is a two-for-one object, comprised of an open cluster (NGC 2175) and an emission nebula (NGC 2174), although most astronomers associate the nebula with NGC 2175. Lying in a rich star field, the otherwise circular nebula is punctured by a dent in its western edge that stands out particularly well in images and helps to form the shape from which this object gets its common name. You’ll need a large telescope to discern the resemblance visually, but a 4- to 6-inch telescope will show the cluster well. � SEEN IT

BETELGEUSE You won’t need star-hopping instructions for our penultimate object, as it is clearly visible to the naked eye, let alone a telescope. Mag. +0.5 Betelgeuse (Alpha (a) Orionis) is the orange-red star at the left shoulder of Orion, the Hunter. This bright supergiant is considered a likely candidate for turning supernova in the near future – though not all astronomers agree on this. Data gathered in recent years has hinted that the star could be shrinking, although it’s possible that this is just an illusion. � SEEN IT

MEISSA Our final object this month is the lovely binary star Meissa (Lambda (h) Orionis), which rests to the northwest of Betelgeuse. Just follow the constellation to find it. Meissa is relatively faint for a star with a common name, but its prominent location as the Hunter’s head has ensured its popularity. It comprises a blue mag. +3.5 primary with a white mag. +5.6 companion separated by 4.4 arcseconds. Through a 4-inch telescope at a magnification in excess of 100x, the pair are a fine sight. There is some mystery associated with Meissa’s name: it originates from the Arabic word for ‘the Proudly Marching One’, although it was not recorded who the marching one was. � SEEN IT

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58 to reach the HD 3807 Group. Unknown to many amateur observers, this delightful asterism is a square of stars with sides about 1º in length. The square is brighter on the southeastern side, where there is a star just outside each corner, and there is a void in the northern quadrant. The brightest star is the easy optical double on the southern corner, mag. +5.9 HD 3807, the body that gives the group its name. Its mag. +8.4 companion is 63 arcseconds to the west. � SEEN IT

BINOCULAR TOUR With Stephen Tonkin Pay a visit to an overlooked asterism, a masquerading galaxy and more  �

5 URANUS

Tick the box when you’ve seen each one

10 x Just past opposition, Uranus is now well50 placed for evening observation and is relatively bright at mag. +5.7. Locate it by hunting down mag. +4.4 star Delta (b) Piscium and then navigating 6º to the southwest. Uranus is the brightest object in the area and is obviously non-stellar. It moves just over 0.5º throughout November, so it should be easy to find on any night. You may be able to spot its gradual motion by comparing its position to the mag. +6.4 star that is just to its left all month. � SEEN IT



about half the diameter of our first target. When you observe NGC 288, remember that you are looking at an object only slightly more than 0.5º from the south pole of our Galaxy. � SEEN IT

1 THE SILVER COIN GALAXY 10 x Nearly 5º to the south of mag. +2.0 star 50 Diphda (Beta (`) Ceti), you will find a right-angle triangle of 5th-magnitude stars. The Silver Coin Galaxy, NGC 253, is nearly 3° to the south this triangle. This bright galaxy appears as an elongated glow – a bit longer than half the diameter of the Moon – with a brighter core. As long as you have a clear southern horizon, it is a relatively easy object for small binoculars despite its low altitude. � SEEN IT

3 TAU CETI 10 x Return to Diphda and navigate just over 50 5º east-northeast to find third-magnitude red giant Tau (o) Ceti. It’s semi-regular variable star, meaning that it is not entirely predictable – its average period is 159 days. The star should begin to brighten over the coming of months, if it is not doing so already. Tau Ceti is also notable as its spectrum contains the element technetium; the most stable isotope, Tc98, has a half-life of 4.2 million years. This is much shorter than the age of the star and provides incontrovertible evidence for stellar nucleosynthesis. � SEEN IT

2 NGC 288 10 x Globular cluster NGC 288, which lies just 50 under 2° to the southeast of the Silver Coin Galaxy in the direction of mag. +4.3 star Alpha (_) Sculptoris, is another easy-ish object so long as you have a good southern horizon. In a pair of 10x50 binoculars, the mag. +8.1 globular is distinctly non-stellar, appearing as a dim circular glow. With averted vision, it seems to grow to

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CHARTS AND PICTURES: PETE LAWRENCE

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THE SKY GUIDE NOVEMBER 59 N

PTOLEMAEUS

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CATENA DAVY DAVY G DAVY Y

DAVY DAVY A ALPHONSUS MARE NUBIUM

Catena Davy TYPE: Crater chain SIZE: 60km long, 3km wide AGE: 3.2 to 3.9 billion years old LOCATION: Latitude 11.0°S, longitude 7.0°W BEST TIME TO OBSERVE: One day after first quarter (evening on 11 November) or one day after last quarter (early morning on 25 November) MINIMUM EQUIPMENT: 8-inch telescope

The catena craterlets are 1-3km wide each, so you’ll need an 8-inch scope to track them down

MOONWATCH With Pete Lawrence “A few members of the chain have odd names, quite unlike those normally found on the Moon: Susan, Osman, Priscilla, Alan, Delia and Harold” THERE ARE A fair number of so-called crater chains visible on the Moon’s surface that can be viewed from Earth. These are typically formed when an incoming body breaks up before the point of impact. As the fragments string out in a line, upon impact they leave a chain of craters. Some of these chains, or ‘catena’, are impressively long. The Catena Abulfeda, for example, measures 220km in length. There’s another rather lovely example close to Crater Davy, which itself lies roughly 200km to the west of the giant 158km walled plain known as Ptolemaeus. Crater Davy measures a modest 36km across and interrupts the western rim of

70km-wide Davy Y. Catena Davy begins roughly in the centre of Davy Y and heads off towards the east, appearing to climb out of Davy Y before coming to a halt at 16km-wide Davy G. The catena consists of 23 craterlets that typically measure 1-3km. There are various theories on how the catena could have formed: the predominant one is that it is the result of a primary impact, caused by a body external to the Moon. Secondary cratering, where material is thrown up from another impact, is thought to be less likely as there are no major impact features along the line of sight of the chain. However, high-resolution spacecraft images have shown that each

crater is cleanly defined compared to its neighbour, with no overlapping regions of ejecta. This has led some lunar geologists to question the impact theory and consider that the catena may be volcanic in origin. A few prominent members of the chain have rather odd names, quite unlike those normally found on the Moon. The largest crater in the centre of Catena Davy, 2.6km wide and 520m deep, was originally known as Davy YA. The craterlets to the east of YA are called Susan, Osman, Priscilla, Alan, Delia and Harold. Unusually, these are the officially recognised titles for these features. Harold is the craterlet closest to the rim of Davy Y, with Susan closest to Davy YA. Susan is also the hardest of the six to spot. The largest craterlet at the western end of the chain was originally called Davy C. Measuring 3.3km across and with a depth of 550m, confusingly both the identity of this craterlet and that of Davy YA are no longer officially recognised by the International Astronomical Union Crater Davy lies to the west of the start of Catena Davy and is not directly connected to the chain that takes its name. Its rim is well formed but interrupted to the south by the younger, 15km-diameter Davy A. skyatnightmagazine.com 2013

60

ASTRO PHOTOGRAPHY With Pete Lawrence

Catch a comet (or two!) Recommended equipment DSLR camera, 50mm lens, equatorial tracking mount, shutter release cable

WITH ALL THE anticipation about comet C/2012 S1 ISON and whether or not it’s going to perform as a bright target, it only seems fitting that this month I should talk about how to go about photographing it. Comets are notoriously awkward objects both in the way they sometimes don’t do what’s expected of them and because they are often poorly placed with respect to morning or evening twilight. A diffuse object against a bright background is a tricky thing to see, let alone photograph. As C/2012 S1 ISON moves toward the Sun throughout November, it’ll also have a bright Moon to contend with from the middle of the month. All these factors aside, putting the effort in and going for the chase can actually be quite exciting. If you’ve had to work hard for a shot, the memory of the effort put in will come back each time you look at it.

There’s a lot going on in the November dawn twilight sky. As well as comet C/2012 S1 ISON, Mercury and Saturn are there too. Dwarf planet Ceres and asteroid 4 Vesta are also in that part of the sky. Periodic comet 2P/Encke will also be nearby. At the start of the month, both comets will be similar in brightness and in the same general area of the sky, roughly 20 º apart. A 50mm lens on a non-full-frame DSLR will cover this area with ease. Head out around 05:00 UT on 1 November and the region you require – just to the south of the Bowl of Virgo, not too far from mag. +2.7 star Porrima (Gamma (a) Virginis) – will be rising in the east. A lovely thin waning crescent Moon (6% lit) completes the picture. See page 51 for positional charts – note that Ceres and Vesta

conveniently lie on a line joining both comets together on the 1st. To start imaging, fully open your lens (set it to its lowest f/number) and select a reasonably high ISO of around 800-1600, composing the shot so that the Moon sits towards the lower right corner of the frame. If your camera is mounted on a fixed tripod, use exposures of 30 seconds or less to avoid significant star trailing. If you are using a tracking system, try 30-second, 60-second, 90-second and 120-second exposures. Shooting RAW images will give you cleaner results.

Tails and trails As C/2012 S1 ISON develops and gets brighter, relatively short exposures should be more successful at capturing it and its (hopefully) developing tail. Short exposures at high- to mid-sensitivity will be essential as the comet gets closer to the Sun from the middle of the month onwards. At this point, the background sky will be bright and easily overexposed. Don’t be afraid of using a lens with a longer focal length than the 50mm initially suggested. This will give you a larger image scale, which will mean the field of view will be smaller. However, it’ll be easier to see the comet. Star trailing kicks in with shorter exposures as the image scale goes up, so if you’re using a fixed tripod, experiment with different lenses and exposures to get the shortest acceptable trails while retaining a bit of detail. If ISON’s tail develops to a significant length, then you’ll need to select the correct lens to allow you to fit it all into one shot.

ALL PICTURES: PETE LAWRENCE

How to image comet C/2012 S1 ISON in twilight

STEP 1 Choose a lens that has a sufficient field of view to allow you to capture the comet plus tail in one go. Be careful because a delicate tail may extend farther than your eyes will show. Fully open the lens at first, but close it by a stop or two if you start to see edge aberrations. Closing the lens will require a longer exposure or higher ISO.

skyatnightmagazine.com 2013

STEP 2 If your camera is mounted on a fixed tripod, then you’ll need to keep your exposures short to avoid significant trailing. If the sky is bright, a high ISO setting may allow a really short exposure of just a few seconds or less. A low to mid ISO and short exposure is the best combination if at all possible, as this will give better tone and less noise.

STEP 3 Focus the lens as accurately as possible. If your lens has auto-focus (AF), turn this on and point your camera at the Moon. Half press the shutter button and let the lens focus. Once done, simply switch to manual focus (MF) and don’t touch the focus ring again. Alternatively, for LiveView enabled cameras, point at a bright star and use LiveView to help you focus.

THE SKY GUIDE NOVEMBER 61

A 50mm lens on a non-full-frame DSLR covers approximately 25º along the long frame axis, while an 80mm lens on the same camera spans 15º. For a smaller tail, say 5º long, a 150mm lens would be ideal. To cope with the changing brightness of the background sky, make use of your camera’s image review facility. As long as an image doesn’t contain large areas of white sky, it should be possible to pull something out of it. A good technique is to note the exposure length that causes this sort of result and then take several shots using progressively shorter exposures, just to be on the safe side. If the sky gets too bright for a high ISO shot, then reduce the ISO. Lower ISO has the advantage of less noise and better tone. Use this technique to maintain the ability to record a strong image, but using a relatively short exposure of 30-seconds or less for cameras on fixed tripods. If the comet’s tail stretches several degrees or even tens of degrees across the sky, you may be able to capture it even when the comet’s head is below the horizon. Although this will not give you a full comet image, it can look very dramatic and will, in the case of the morning shots before and after perihelion, allow you to shoot the tail against a slightly darker sky than normal. Finally, think about the composition. With a brightening sky background there are some objects, such as trees, that can add great atmosphere to the shot. Just make sure whatever you choose doesn’t get in the way and block your view of the comet itself though.

STEP 4 Take a 30-second exposure. If the shot contains white, reduce the ISO and repeat. If you reach ISO 400, reduce the exposure instead. Check this regularly as the twilight changes. If possible, check your camera’s image information display for overexposure in the sky. Use RAW for better results. If you prefer JPEG for quick viewing and manipulation, use RAW+L (large) JPEG.

Remember, a delicate tail may stretch for longer than you can see with the naked eye alone

Key technique MAKING THE MOST OF THE REVIEW SCREEN Twilight conditions can be very testing because of the ever changing light levels, so the review screen is indispensable. Most cameras are able to display some information about an image; if you’re unsure, check your camera’s manual. A histogram display is ideal – if the curve truncates at the white end of the graph, then there is overexposure. If it truncates at the black end, you’ve had some underexposure. Ideally, the curve should rise and fall smoothly between these two extremes but some overexposure (white) may be acceptable in the head of the comet.

Send your image to: [email protected]

STEP 5 Once you have found an exposure that gives a bright but not overexposed image, take several shots, reducing the exposure between each. It’s a good idea to take at least several sets of images over the course of a session. Download the images to a computer and review to pick out the best one. Open this in a layer-based graphics editor and duplicate the base layer.

STEP 6 Work on the upper duplicate. Open the Levels tool and drag the black and white control points to the ends of the main data curve, as above. Tweak position of the mid-point slider to give a pleasing, higher contrast result. If your software supports it, additional detail can be teased out by duplicating this layer, setting blend mode to ‘Overlay’ and applying a high-pass filter.

skyatnightmagazine.com 2013

THINKSTOCK, LIBRARY OF CONGRESS/SCIENCE PHOTO LIBRARY, ROYAL ASTRONOMICAL SOCIETY/SCIENCE PHOTO LIBRARY

The demon of autumn Heather Couper explores the secrets of Algol, the blinking star in Perseus that has enchanted humans for generations

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Algol is commonly represented as the head of Medusa; it is much maligned as a star of ill-fortune and despair

s variable stars go, it is perhaps the most iconic in the night sky. Every stargazer has heard of the ‘winking demon’ in Perseus thanks to its regular changes in brightness from mag. +2.1 to mag. +3.4, occuring every 2.87 days. Commonly known as Algol, designated Beta Persei, it marks the severed head of the Gorgon Medusa, held aloft by the Greek hero as he soars across the sky. The Ancient Greeks referred to this star as the ‘evil eye’ – somewhat unsurprising given that meeting Medusa’s gaze was said to turn you to stone. But the truth is that Algol seems to have been a suspect star for millennia. Its common name stems from the Arabic ‘Al Ghul’, from which we get the word ghoul. To the Chinese it is ‘Tseih She’, meaning ‘piled-up corpses’. Historically, Algol seems to have been a byword for bad luck, death and putrefaction. Maybe our ancestors would have felt better if they had known the reason for the demon’s winking. Algol is not one star, but a system of three: a close binary with a slightly removed companion. The orbital plane of the binary pair happens to match our line of sight from Earth, so they appear to eclipse each other – hence its variability. We call stars like Algol eclipsing binaries (see box, overleaf). Algol also lends its name to an entire class of variable stars of this type, which are known as Algol variables. Our knowledge of Algol has come along in fits and spurts. The first person to systematically log its variability was

Italian astronomer Geminiano Montanari in the 1670s. Then a little over a century later, in 1782, a gifted and profoundly deaf young astronomer picked up the trail. John Goodricke lost his hearing as a result of a severe illness in childhood. He was born in 1764 in the Netherlands but schooled in Edinburgh and Warrington, after which he joined his parents at the family’s ancestral home in York, >

>

< Goodricke was shocked by the speed at which Algol dimmed when he first saw its variability

“The shape of Beta Persei B has been distorted into a teardrop by the powerful gravitational attraction of Beta Persei A”

> Ribston Hall. They happened to live

next door to one Edward Pigott, whose father had built a modern observatory in his grounds. Pigott was interested in variable stars and his enthusiasm captured the fascination of young Goodricke, then just 17. The pair soon conspired to work through Pigott’s watch list of variable and potentially variable stars, which included Algol. Goodricke is credited for realising what no one else had – that Algol was varying at regular intervals. After several months of observations he had calculated its periodicity as being a little less that two days and 21 hours; he also proposed a mechanism for the dimming, the presence of a large body that blocked some of its light. In May 1783 Goodricke presented his findings to the Royal Society, for which he was awarded the Copley Medal for outstanding achievements in science. On 6 April 1786, the society elected him to fellowship. Tragically, what promised to be a bright career was cut short. He died of pneumonia a fortnight later, aged 21.

MARK GARLICK/SCIENCE PHOTO LIBRARY, ILLUSTRATION BY STEVE MARSH

The second body mystery We have to fast-forward another century and hop to Germany for our next leap of understanding. In 1889, at the Astrophysical Observatory Potsdam, pioneering spectroscopist Hermann Carl Vogel measured the Doppler shifts of Algol’s spectral lines. From this, he was able to confirm that the large body that Goodricke had theorised was in fact a second star. Blue-white Beta Persei A is a main sequence star and the brighter of the binary pair. Its close companion, Beta Persei B, is a dimmer red subgiant. The periodic dimming that is so familiar to us marks primary eclipse, when the red subgiant passes in front of the brighter, younger star. There’s also a secondary eclipse, where the positions of the two stars are reversed, but the magnitude drop is so slight it can only be detected with sensitive instruments.

Algol’s tempestuous nature stems from interactions between the binary pair

The stars share a tight embrace, being separated by just 9.3 million km. This proximity explains why the primary eclipses are so frequent, occurring every two days, 20 hours and 49 minutes. The third star in the system, Beta Persei C, was discovered spectroscopically in 1912. It keeps its distance from the binary, taking 1.86 years to orbit them. The Algol system holds more surprises. Beta Persei A is presently 3.6 times the mass of our Sun, while Beta Persei B is only 0.8 solar masses. So how is it

that Beta Persei B has already become a red giant, while Beta Persei A remains a normal-looking young star? Stellar theory predicts that the star with the greater mass should evolve first. “Isn’t it striking that one of the best-studied star systems still has riddles to solve?” says Algol expert Larry Molnar, professor of physics and astronomy at Calvin College in Grand Rapids, Michigan. He reveals that there is name for this phenomenon – it is called the Algol Paradox.

ALGOL NOVEMBER 65

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1

Time Period (2.87 days) 1. PRIMARY ECLIPSE The dimmer star passes in front of the brighter one, reducing the amount of light emitted by the system overall. The eclipse causes Algol’s brightness to drop from mag. +2.1 to mag. +3.4 and back.

“The paradox of the Algol system is that it’s the low mass star that has evolved, run out of hydrogen fuel and moved onto the red giant phase,” he says. “The resolution is that the original masses must have been reversed in the past, with Beta Persei B having 3-4 solar masses, while Beta Persei A had only 0.5-1.5.” It’s the close proximity of the binary pair that appears to set Algol apart. “As Beta Persei B was beginning to swell up, material in the outer layers of the star began to fall onto Beta Persei A,” Molnar

2. SIDE BY SIDE Between eclipses, Algol shines steadily at mag. +2.1, almost as bright as the pole star. At this point the two stars are side by side from our perspective on Earth, so we see the light from both of them.

3. SECONDARY ECLIPSE Farther along the orbit a second eclipse occurs, this time when the brighter star moves in front of the dimmer one. In Algol’s case, the change in the brightness we see is minuscule – about 1/20th of a magnitude.

continues. “This led to a dramatic transfer of most of Beta Persei B’s mass in a very short time; as such, the shape of Beta Persei B has been distorted into a teardrop by the powerful gravitational attraction of Beta Persei A.”

of Beta Persei A forces it to rotate at the orbital period of 2.867 days, more than 10 times faster than our Sun, which causes particularly strong magnetic loops to form. As these loops are pushed against each other, they can short out electrically, converting the magnetic energy into the kinetic energy of charged particles. These high-energy particles emit the radio waves and X-rays we see as flares.” Eventually, Beta Persei B will fling off its unstable outer atmosphere and expose its nuclear core to the cosmos as a white >

A stormy relationship The interaction between the two stars creates a stormy environment; the system explodes with radio and X-ray flares. “Beta Persei B has a strong magnetic field,” says Molnar. “The tidal influence

THE EXPERT Larry Molnar, professor of physics and astronomy at Calvin College in Grand Rapids, Michigan, tells us how we still have so much more to learn about the Algol system How distinctive is the Algol system? While the majority of stars have binary companions, most of them are well enough separated not to have gone through what has happened to Algol. At the same time, there are so many stars in the Galaxy that there are probably many thousands like Algol. What’s distinctive for us is that the plane of Algol’s orbit is within 9° of our line of sight. Hence we see a dramatic

change in brightness when the cooler star eclipses the hotter star. What can we say about the future evolution of the system? This is still a big unknown. One reason is the third star, Beta Persei C. It is 1.5 times the mass of our Sun and orbits the close pair in just 680 days. But sorting out the exact orbits of the three components has been a challenge. Indeed, only with the recent development of the Navy Prototype Optical Interferometer has it been possible to individually resolve all three stars separately. The third star will likely have a significant influence on the long-term outcome, but exactly how remains to be seen.

Are there any other riddles about Algol? Within a year, John Goodricke had determined the length of the orbital period to within an uncertainty of 10-15 seconds. One might think that, 230 years later, we would have nailed the period to a much greater accuracy. However, the orbital period isn’t steady. Over the centuries, observers have noted the timing of eclipses, and found that the period will sometimes suddenly increase or decrease in an apparently random way – for reasons not yet clear. Continued monitoring of period changes (including those by amateur astronomers) will be important to finally solving this final conundrum.

skyatnightmagazine.com 2013

a You can spot Algol’s fading and brightening by comparing it to the other stars in Perseus

WHEN TO WATCH THE DEMON DIM

Mirphak _

.4) on the mest point (mag. +3 Algol falls to its dim to see it wax le ab be ’ll vember; you following nights in No these times. of l hours either side and wane for severa

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5 UT 1 November at 02:3 4 UT 3 November at 23:2 UT 6 November at 20 :12 UT :17 21 November at 04 :06 UT 24 November at 01 .55 UT 26 November at 21

PERSEUS

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> dwarf. If Beta Persei A heaps enough

` Algol

matter on it, that zombie star will explode as a Type Ia supernova. Until that happens, it’s a great observing target.

Heady delights l

HOW TO FIND ALGOL Algol (Beta (`) Persei) is both bright and visible all night long in November. To find it, look for the obvious shape of Taurus and home in on the Pleiades. From there, shift

your gaze and identify the familiar W-shaped constellation of Cassiopeia. Algol lies halfway between the Pleiades and mag. +2.6 Ruchbah (Delta (b) Cassiopeiae).

CASSIOPEIA

M31

Ruchbah

ANDROMEDA M33

CHART AND PERSEUS PICTURE: PETE LAWRENCE, THINKSTOCK

CAMELOPARDALIS

Almach

TRIANGULUM

Mirphak Algol

ARIES

Algol remains high in the night sky this month, and the fact it is so bright and dims so regularly makes it a great first variable star for beginners. You can catch it waxing and waning on several occasions during November (see ‘Watch the demon dim’, above). Each primary eclipse lasts for 9.6 hours. If you have trouble spotting Algol’s variability, a good comparison star is its neighbour, mag. +2.9 Epsilon Persei. Before Algol fades it is the brighter star, but at its low ebb it is the dimmer of the two. As for equipment, less is more, says Roger Pickard, variable star director at the British Astronomical Association. “The best way to observe Algol is with the naked eye,” he enthuses. Algol sits 93 lightyears from Earth, but this hasn’t always been the case. Just over seven million years ago it swung past us at a distance of only 9.8 lightyears. With a combined mass of 5.8 times that of the Sun, it is possible that the gravity of its three stars deflected some comets from the Oort Cloud towards the inner planets. But there’s little evidence for a heightened level of impacts on Earth as the winking demon passed by. Perhaps it’s not so monstrous after all. S

PERSEUS

ABOUT THE WRITER Capella Pleiades

AURIGA

TAURUS

Perseus can be easily found by using obvious Cassiopeia and the Pleiades as signposts

skyatnightmagazine.com 2013

Heather Couper is an astronomy author and broadcaster. Her latest book is Philip’s Stargazing 2013, which is co-authored with Nigel Henbest.

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Skylab

THE FINAL MISSION Mark Bowyer looks back at the last visit to America’s first space station

Skylab, built from a section of a Saturn V, remained in orbit for just over six years

NASA

F

ormer US President John F Kennedy achieved his goal of landing a man on the Moon in 1969. After this historic event, NASA busily began looking for ways to use the resources that had been created during the Apollo years – and the result was Skylab. By the middle of the 1960s it became apparent that, in order to maintain its skilled workforce, NASA needed a post-Apollo plan. Despite many suggestions, NASA was beginning to feel the effects of budget cuts as politicians wondered if money could be better spent on Earth. One idea that endured was a relatively cheap orbiting workshop made by converting the upper stage of a spent booster into a habitable space for long-duration missions. However, early flights had shown how difficult it is for an astronaut to work in space unless properly restrained. The favoured solution was to convert the S-IVB upper stage – essentially a fuel tank – of a Saturn V rocket on the ground and launch a space station that was ready to receive a crew. It remained uncertain how many Saturn V’s would be needed for Apollo now that NASA could no longer afford any more, but early success and a reduced Apollo test programme kept the idea alive. Finally the announcement was made on 22 July 1969, as Neil Armstrong and his crew began their return journey to Earth after landing Apollo 11 on the Moon: a Saturn V would be converted into Skylab. Aerospace manufacturer McDonell Douglas carried out the work to convert the hydrogen tank of the third stage S-IVB >

70

The final mission gets underway in November 1973

> into a workshop to house three astronauts. Two flight-ready stations were built, although the second mission, Skylab B, was eventually cancelled due to lack of funding. It can now be seen in the National Air and Space Museum in Washington.

The crew were all smiles on the ground, but conflicts with Mission Control would erupt in orbit

An all-rookie crew of commander Gerald Carr, pilot William Pogue and scientist Edward Gibson made up the third and final Skylab mission – Skylab 4. Being the final mission, scientists lobbied for a host

of new experiments to be carried, which left little time for crew training. Skylab 4 launched for its 84-day mission on 16 November 1973 following a five-day delay, after cracks were found in the launcher’s stabilising fins. The launch and ascent was flawless, but as soon as Pogue left his seat on reaching orbit, he felt unwell. Despite a reputation on the ground

for an iron stomach, Pogue soon found he needed a sick bag. Worried that this might cause Mission Control to delay them from entering Skylab, Carr simply reported that his crewmate had felt nauseous. The automatic tape recorder downloaded their discussion and Alan Shepard, head of NASA’s Astronaut Office gave them a mild rebuke for withholding this information.

Carr took this image during the final Skylab spacewalk – his tether can be seen bottom left

Gibson demonstrates zero gravity by soaring thourgh a hatch, Superman-style

The Orbital Workshop was Skylab’s heart, a space used for work, rest and storage

NASA X 8, THINKSTOCK

The last lift-off

SKYLAB

TIMELINE

SKYLAB 1 14 May 1973

SKYLAB 2 25 May

4 June

7 June

The space station was launched in a mission designated Skylab 1; the Skylab 2, 3 and 4 missions were all manned. A comms breakdown meant the crew patches had the numbers 1, 2 and 3 instead.

Skylab launches from Kennedy Space Center, as the modified third stage of the last Saturn V to fly. Calamity struck quickly, with the micrometeroid shield lost and solar panels damaged en route to orbit.

The first crew – commander Charles Conrad, pilot Paul Weitz and scientist Joseph Kerwin – follow the Skylab into orbit, 11 days later than planned due to the problems with the initial launch.

The first crew discover that the temperature inside Skylab is a sweltering 54ºC. By deploying a parasol through the experiments airlock, they are able to reduce this to 26ºC.

Astronauts Conrad and Kerwin leave the airlock to try and free the remaining solar array. They are able to do so using a device based on a pruning tool, allowing it to deploy.

skyatnightmagazine.com 2013

SKYLAB SKYLAB NOVEMBER 71 TIMELINE DISASTER STRIKES

More zero-gravity japes: Carr balances Pogue on the end of his finger with ease

Skylab 4’s highly detailed flight plan had been influenced by the high work rate of the previous two crews; Carr, Pogue and Gibson found it difficult to keep up as they struggled to adjust to living in space. Unfamiliar experiments also added to the pressure. The first of three spacewalks occurred on 22 November when Pogue and Gibson restocked the telescope cameras with film and tried to free a stuck antenna. The first job proved easy thanks to well placed foot restraints but no one had planned for other running repairs, and to reach the antenna Gibson had to hold Pogue’s legs and move him into position.

Snapped solar panels and flailing cables awaited the Skylab 2 crew on arrival During Skylab’s launch, Mission Control noticed a brief anomaly in the telemetry, but it wasn’t until they started to activate the station that the cause became apparent. The thermal and micrometeoroid protection shield had been torn free, taking one of the main solar arrays with it. To make matters worse, debris prevented the second array from deploying. The dilemma facing NASA was that to produce power, the remaining solar panels needed to face the Sun but that in turn caused Skylab to overheat. Almost 25 per cent of the total manoeuvering fuel for the mission was used balancing power and temperature concerns while a solution was devised.

The first crew, launching 11 days late, took a reflective parasol that would deploy through one of the experiment airlocks. When entering, the crew reported a desert like dry heat as high as 54ºC and had to use their Command Module as living space until the station cooled to a more acceptable 26ºC. As no one had foreseen the need for inflight repairs, working outside on the jammed solar array proved difficult. A temporary restraint had to be used as a long handled cutter was positioned to remove the debris. Without these repairs Skylab would have been an embarrassing failure.

Owen Garriott makes repairs during the Skylab 3, continuing to fix the inital damage

Tensions mount The record-breaking duration of the mission – more than 20 days longer than Skylab 3 – seemed in doubt the next day when one of three control gyros failed. Mission Control had to learn how to orientate the station using the remaining two. The crew’s frustration became apparent in early December, when Carr requested a frank discussion with the ground. He decided that the crew would spend as much time as needed for each task and asked that routine housekeeping be done at their discretion. With a more fluid approach to the timetable, the crew felt better able to cope, and their work rate soon increased as a result.

December also saw the arrival of comet Kohoutek, which the crew observed from their unique position. Gibson was able to add to our understanding of the Sun by recording a solar flare from its formation, and the whole crew took part in numerous medical experiments and Earth observations. On 8 February 1974, the crew deactivated Skylab, left some samples in the airlock for a future mission to retrieve and started the long descent back to Earth. Despite plans for a visit by an early Shuttle flight, delays to that programme made it impossible. Skylab eventually

22 June

SKYLAB 3 28 July

25 September

The first crew returns after 28 days in space – a record breaking duration. They carried out 392 experiments during their 404 orbits plus three spacewalks, travelling a total of 18.5 million km.

The second crew of commander Alan Bean, pilot Jack Lousma and scientist Owen Garriott launch for their 59-day mission. All three men suffered motion sickness early in the flight.

The second crew install a sunscreen outside Skylab to augment the parasol and perform other maintenance. They carried out 1,081 hours of Sun and Earth observations before returning home.

deorbited on 11 July 1979, with some debris hitting the ground in sparsely populated Southern Australia. The many lessons learned from Skylab are used to this day in planning and operating the International Space Station. S

SKYLAB 4 16 November 1973 to 8 February 1974 The final mission was the longest yet, almost 50 per cent longer than Skylab 3. It taught Mission Control that planning every minute of the crew’s time could be counterproductive.

ABOUT THE WRITER Mark Bowyer is an expert in the Apollo missions and the later use of Apollo hardware. He spends most of his observing time looking at the Moon.

10 July 1979 Skylab’s controllers change the orientation of the space station as it nears re-entry to try and minimise the risk of debris falling on populated areas. Parts of it land in Southern Australia.

skyatnightmagazine.com 2013

COMET

SPECIAL

Comets BIOCHEMICAL COURIERS New research has strengthened theories that the ingredients for life could have been brought to Earth by comets. Will Gater investigates

W

e humans have a strange relationship with comets. Historically they’ve been seen as portents of terrible things to come and, even today, we depict them in movies destroying cities and threatening humankind. But this lingering notion of comets as harbingers of destruction isn’t the whole picture. Numerous lines of scientific research are now underpinning the theory that comets played a vital role in the formation of life on Earth, and with C/2012 S1 ISON making its way through the inner Solar System now’s the time shed a light on the alternative view of these celestial visitors – as the delivery system for the chemistry that sparked life. Look up into the night sky and, if you have dark skies, you’ll see nothing but inky blackness between the stars. We like to think of space as being a vast expanse of emptiness, of nothing. But the reality is that interstellar space contains an enormous amount of gas and dust, and it’s this material that’s the key to understanding why comets are so fascinating to astrobiologists studying the genesis of life. “Comets are aggregations of interstellar dust particles,” says Dr Richard Mathies from the University of California, Berkeley. “This is not the kind of dust you find in your house when you shake a sheet or something like that. These are relatively clean dust particles that are aggregates of small molecules like carbon dioxide, water, ammonia and hydrocarbons.”

Comets bombarded the early Earth – perhaps bringing the molecules vital for life with them

Astronomers have known for years that these molecules can be found in space, and it was also understood that irradiating them could create amino acids, commonly known as the ‘building blocks of life’. “The real question is ‘what happens next?’” says Mathies. Specifically, Mathies and his colleagues at Berkeley and the University of Hawaii, Manoa, wanted to find out what’s needed to create polymers – chains of amino acids. “The basis of life is the formation of combinatorial polymers,” says Mathies. “That’s the basis of peptides and proteins, that’s the basic structure of nucleic acids (RNA and DNA) and it’s the basic structure of sugars. You take simple molecules and you make various combinations of linear chains and this gives you a way of generating tremendous molecular complexity.” >

TAKE 27 LTD/SCIENCE PHOTO LIBRARY

Forging the chain

Comets are largely made of interstellar dust, which is quite unlike what we call dust on Earth

“The idea of a comet smashing into Earth will no doubt evoke images of Armageddon”

NASA/JPL-CALTECH/T. PYLE (SSC), THINKSTOCK X 2, ESA/MPS, NASA/JPL, NASA/JPL-CALTECH/ UMD X 2, NASA, ESA AND PHILIPPE LAMY (LABORATOIRE D’ASTRONOMIE SPATIALE)

> To explore what could make the polymers,

the team went about recreating the environment found in interstellar space with the help of a vacuum chamber. Inside the chamber the team placed a small disc of silver measuring roughly 2cm wide and a few millimetres thick. This silver would be the surface on which the team could reproduce the same chemistry that’s thought to be occurring on interstellar dust particles – and it would be here that they’d look for the secrets of polymer formation.

The acid test With the air pumped out of the chamber to simulate the vacuum of space the piece of silver was cooled to around –260 º C. Then a cocktail of ingredients known to be present in interstellar dust particles was pumped into the chamber in a gaseous form: this mix included methane and ethane (hydrocarbons) as well as ammonia and carbon dioxide. “It’s so cold that the gas condenses on the silver very rapidly and forms a film – an aggregate of all of these,” says Mathies. “It’s like water vapour condensing on a window in the winter and making an icy film. That’s exactly what’s going on.” skyatnightmagazine.com 2013

A present-day comet strike may not be the end of the world, but it would wreak considerable havoc

But the film only simulated what’s found in the dust particles themselves. To complete the experiment the team needed something else. In space, the dust would be bombarded by high-energy particles known as galactic cosmic rays; these play an important role in the reactions that occur on the dust particles, explains Mathies. “When the carbon dioxide, ammonia, water and hydrocarbons are blasted by galactic cosmic rays they get activated and can make new molecules,” he says. To recreate this extreme bombardment the team fired electrons at the icy sample, then analysed it to see what had been made. The result was remarkable. “What we’ve shown is that, once you make amino acids in these ices the continued irradiation with galactic cosmic rays also leads to the formation of simple polymers – the first step in the evolution of more complex molecules,” says Mathies. In space those complex molecules could find their way into comets as the dust particles clumped together and eventually, it’s thought, those comets that may have eventually collided with the young Earth.

While the work of Mathies and his colleagues paints an incredible picture of the reactions that are likely to be occurring on interstellar dust particles, the idea of a comet smashing into Earth will no doubt evoke terrifying images of Armageddon for many. Yet in our planet’s distant past these violent collisions may have been the sources of yet more intriguing chemistry. Dr Nir Goldman from the Lawrence Livermore National Laboratory and Prof Isaac Tamblyn from the University of Ontario Institute of Technology have been examining what reactions might have occurred at the heart of a comet as it slammed Earth. “Comets contain a lot of raw material that could be useful for prebiotic chemistry – the chemistry of the building blocks of life – and the impact contains a lot of energy,” explains Goldman. This energy can drive chemical changes. “Prebiotic materials, like amino acids for example, have fairly high energetic barriers for their formation. If things happen in the right way this raw material gets just enough energy to push it over these barriers. You start with very simple things and then the impact event carries it one step higher in complexity.” The impact itself produces an incredibly powerful compression wave inside the comet, which results in extraordinarily high temperatures and pressures. Yet just how extreme the conditions are during impact depends largely on the angle the comet strikes at, says Goldman, and that has important implications for the chemistry going on inside it.

CLOSE

ENCOUNTERS COMET HALLEY X Comet Halley last passed through the inner Solar System in 1986. Several spacecraft were sent to study it up close including, most famously, ESA’s Giotto probe; it returned spectacular, detailed images of the comet’s active nucleus.

W COMET WILD 2 Wild 2 was the target of NASA’s Stardust mission, which flew close to the comet in January 2004. The spacecraft had a special collector mounted on board that caught samples from the comet and returned them to Earth in a capsule.

Impact intrigues

COMET TEMPEL 1 X In July 2005 NASA’s Deep Impact spacecraft sent a 370kg probe crashing into Comet Tempel 1 in order to study the structure and composition of the icy body. The impact produced a bright flash that was captured by the spacecraft’s cameras.

W COMET HARTLEY 2 Five years after its encounter with Tempel 1 the Deep Impact spacecraft, by then renamed the EPOXI mission, flew past Comet Hartley 2 at a distance of roughly 700km. EPOXI’s cameras revealed jets bursting from the comet’s nucleus.

COMET 67P/ CHURYUMOV-GERASIMENKO X In November next year ESA’s Rosetta mission will fire a lander onto the surface of comet 67P/Churyumov-Gerasimenko. The lander is equipped with several instruments including one capable of looking for complex organic molecules.

TO E H N C O AT W

“If a comet were to make a direct impact with a planet, this that could yield extremely high temperatures [around 10,000°C] and pressures, and it’s not clear that any interesting chemistry could happen because the conditions are so intense,” explains Goldman. “Now if the comet comes in at a shallower angle, let’s say 20 º, then the conditions are much tamer. The temperature might be more like 3,000°C, while the pressure is more in the order of 300,000 times normal atmospheric pressure. That’s very hot and very compressed, which promotes reactivity, but not so hot that everything just gets obliterated.” With the help of a supercomputer, Goldman and Tamblyn were able to model the chemical reactions that resulted within a comet undergoing these searing temperatures and crushing pressures. “[Our simulations] zeroed in on an icy grain deep within the comet,” says Goldman. The computer models showed that several biologically significant materials can be formed in the turmoil of a cometary impact. “We see things like precursors to amino acids, amino acids and aromatic compounds such as carbon ring structures, which are very stable rings of carbon molecules,” says Goldman. The results of Goldman and Tamblyn’s simulations are perhaps most interesting when >

Much of our understanding of comets has come from missions that have visited them as they enter the inner Solar System.

76 DID COMETS BRING LIFE TO EARTH? NOVEMBER

Beyond their potential as chemical catalysts, comets may have brought water to Earth

WATERY WANDERERS

> they’re considered in the context of what was

occurring in the chaos of the early Solar System. “There were periods of heavy bombardment in which trillions of tonnes of organic material could have been delivered to the early Earth per year,” says Goldman. “That’s a really fascinating thing to ponder because the cometary material is likely to have collided with Earth at all sorts of different angles – yielding a wide variety of impact pressures and temperatures – which ultimately could have produced an enormous amount of different kinds of chemistry.” Yet for all we’ve found out about cometary chemistry the question of how life itself arose on the Earth still remains. “There’s a huge gap in our knowledge,” says astrobiologist Dr Louisa Preston. “We get the chemistry and we get what life needs but what was that moment that it became biology?” On that question, just like the comets out in the distant reaches of the Solar System, we may be in the dark for some time to come. S

Each impact would have created different heat and pressure conditions – and, possibly, different molecules

Comets have not only been implicated as bringers of organic molecules to the young Earth; many scientists believe they could have also delivered the water that makes up the oceans that we see today. Researchers can’t go back in time to prove this of course, but they can look at what’s happening elsewhere in the Galaxy. Recently, astronomers used the Herschel Space Observatory to observe DG Tau, a baby Sun-like star roughly a million years old. “The star is surrounded by a disc of gas and dust that could form a planetary system like our own,” says Dr Linda Podio. She and her colleagues discovered vast amounts of water in the outer reaches of DG Tau’s disc. “The detection is important because it shows that in the outer disc region, where comets are believed to form, there is enough water to form an Earth ocean. Of course, this is only a little piece of the puzzle and more observations and theoretical studies are needed to confirm this scenario.”

ABOUT THE WRITER Will Gater is an astronomy journalist and author with a degree in astrophysics from University College London. Follow him on Twitter: @willgater.

NASA/JPL-CALTECH/R. HURT (SSC)/SCIENCE PHOTO LIBRARY, THINKSTOCK

THE EXPERT Astrobiologist Louisa Preston of the Open University tells us why comets hold so much allure for scientists and why we should be excited by their fascinating chemical composition Why are comets especially interesting to astrobiologists? Comets are remnants from the early Solar System, and outside the Solar System, so they freeze in time ancient conditions. Because they are full of ice, predominantly water-ice, they have the ability to bring water with them if they crash into the Earth or another planetary body. This ice and water can contain many of the small molecules that we think prebiotic chemistry

skyatnightmagazine.com 2013

on Earth would have needed. They also incorporate dust and we know, from studying dust grains in space and in meteorites, that organic molecules can be preserved and held within these dust grains. What particular molecules are commonly found in comets? Mainly it’s the carbon and nitrogen molecules. They are the ones we are most interested in because they are the most important for terrestrial biology. We think you can find ammonia, methanol and methane. Also the different types of ice could be water, carbon monoxide, carbon dioxide, hydrogen

cyanide – a lot of different combinations of carbon, hydrogen and nitrogen basically. Why are they interesting from a life perspective? Carbon and nitrogen are two of the most important elements for life. Proteins, for example, are made up of amino acids and amino acids need nitrogen. So we know these elements are important. Glycine was found in dust samples from Comet Wild 2. Glycine is effectively the smallest amino acid found in proteins on Earth. So it’s very interesting that inside this comet we find an amino acid that’s actually found inside proteins that make up life on Earth. That’s the link and that’s why these are so important to us.

78

Skills

Brush up your practical astronomy prowess with our team of experts

Contents The guide

How to

Sketching

Scope doctor

78

81

85

87

We look at the Oort Cloud, a giant comet reservoir we’ve never seen

Build an adaptor to hold your smartphone steady while imaging afocally

Learn how to sketch edge-on lenticular galaxy NGC 7332 in Pegasus

Steve Richards answers your astro equipment queries

SKILLS

The guide

COMET

SPECIAL

The Oort Cloud With Paul Sutherland

Explore the hypothetical source of comets like C/2012 S1 ISON

This spherical reservoir could hold trillions of icy bodies, some of which will surely become ‘Great Comets’

Oort Cloud

30 AU

50 AU

150,000 AU

1 AU = 150 million km

SCIENCE PHOTO LIBRARY, CLAUS LUNAU/SCIENCE PHOTO LIBRARY

MIKKEL JUUL JENSEN / SCIENCE PHOTO LIBRARY, SCIENCE PHOTO LIBRARY, JERRY LODRIGUSS/

0 1 AU

Proxima Centauri 250,000 AU

Solar System Kuiper Belt

SOLAR SYSTEM AND KUIPER BELT RELATIVE SIZES NOT TO SCALE

skyatnightmagazine.com 2013

SKILLS NOVEMBER 79

E

veryone is looking forward fairly insubstantial individually, together to what will hopefully they could add up to several times be a spectacular the mass of the Earth. appearance by Some of the most Comet C/2012 S1 ISON impressive long-period in the weeks ahead. But and non-periodic comets as with many of the are thought to have great comets before it, started their journeys we’ve only been aware here, after being of this icy visitor for a dislodged by some short time. Unlike the unknown event. The familiar and reliable Oort Cloud is thought planets, comets like this to have sent us comets one often seem to appear C/1996 B2 Hyakutake, C/2011 from nowhere. L4 PANSTARRS and now, C/2012 So where exactly did it come Þ Jan Oort proposed the S1 ISON. But it is not the only from? The answer, it seems, is existence of the mystery source of them. Short-period ‘cloud’ in 1950 from a vast reservoir of icy comets are thought to come bodies, numbered in their from somewhere much closer billions – perhaps trillons – that make up a ghostly shell around the entire Solar System. Comet Hyakutake, the ‘Great Comet of 1996’ is Though it has never actually been also from the Oort Cloud observed, this spherical region is named the Oort Cloud after Jan Oort, the Dutch astronomer who suggested its existence in 1950. He did so to explain the appearance of comets with orbital periods of many thousands of years – reviving a similar idea that had been proposed by Estonian astronomer Ernst Öpik 18 years earlier.

– a region beyond Neptune called the Kuiper Belt and the area just beyond it known as the ‘scattered disc’. We don’t have any observations to confirm whether the Oort Cloud exists or not, and it is too far to study with space probes – Voyager 1, which NASA recently announced has crossed into interstellar space, will not reach it for hundreds of years, by which time it will be long past its useful life. Even New Horizons, on its way to Pluto and the Kuiper Belt, will be unable to help us. But the theory that the cloud exists is a neat one, explaining how these icy Solar System leftovers come to grace our skies. S Paul Sutherland is a space journalist and science writer

Massive mystery It has been suggested that the Oort Cloud begins at around a lightyear’s distance from the Sun and may stretch as far as a third of the way to the next nearest star, Proxima Centauri. It is a region filled with frozen fragments of water, ammonia and methane left over from the formation of the Solar System and, though the fragments are

THE START OF THE JOURNEY What triggers the dislodging of an icy object in the Oort Cloud to send it hurtling into the inner Solar System? Astronomers say that, in such a remote zone far from any giant planets and where even the Sun has little effect, the slightest external force can influence these bodies. One such force could be the pull of the Milky Way, termed the galactic tide. But a passing star or gas cloud might similarly alter the orbits of frozen chunks, sending them sunwards, as shown on the right. Even collisions between the objects themselves could set them on a new course towards the inner Solar System.

Some astronomers believe, however, that there could be a sizeable object within the Oort Cloud itself that is disturbing it – a hypothetical gas giant that may be several times the size of mighty Jupiter. This potential ‘ninth planet’ even has a name, Tyche. Its existence was proposed in 2002 to explain why one part of the Oort Cloud appears to be sending us more comets than others. The theory remains highly controversial, but if Tyche does exist there is the chance it might be discovered in archived observations of from NASA’s WISE mission, which has imaged much of the sky to reveal cold asteroids and similar objects.

skyatnightmagazine.com 2013

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SKILLS NOVEMBER 81

SKILLS

How to

Make your own smartphone adaptor With David Utting

It’s amazing what you can do with a few bits of old metal

TOOLS AND MATERIALS

FINISH

Glue some felt along the inside to avoid scratching. MATERIALS

Wood for the template, a thin sheet of metal for the mount, plus felt lining. SUNDRIES

You need two threaded bolts, two wing nuts and four washers to assemble the adaptor, plus a longer bolt and a captive nut to secure the clasp around the focuser drawtube or eyepiece body. TOOLS Using wing nuts to assemble your adaptor lets you swap eyepieces without needing tools

ALL PICTURES: DAVID UTTING

G

one are the days when the camera on your mobile phone was only capable of producing fuzzy, low-res images. Some are now so good they rival dedicated point and shoots, and can be used with a telescope to image brighter targets like the Sun, Moon and planets. Their large displays make group observing much more fun, while internet connectivity and apps make it easy to edit and share your shots quickly. Using a smartphone to snap the night sky relies on ‘afocal’ imaging, meaning the camera is placed in front of the eyepiece instead of replacing it. But lining up a phone lens with a telescope eyepiece for a stable

A hammer, drill, bevel, ruler, hacksaw, file, metal cutters, pliers, glue and lathe centre.

shot can be tricky. You can buy brackets, but here we’ll show you how to make a sturdy, adjustable adaptor that is compatible with a range of eyepieces. It’s comprised of three parts: a phone holder, a telescope clasp and a bracket to link the two.

Start with templates You need to make two wooden templates, one for your smartphone and another that matches the diameter of your eyepiece’s body. Jot down the dimensions of your smartphone, then saw a block of wood to those measurements to make a template. Do the same for the eyepiece; alternatively, you could use an old eyepiece barrel instead.

We used aluminium from the back of an old computer case for our phone holder, but you could use a different metal so long as it is sturdy but can still be cut to shape. Cut your metal 2cm larger than the surface of your phone and bend the surplus over the edges of your wooden phone template – this creates the metal tabs that will hold the phone securely in place. Use a hacksaw to remove a small section on the back so that the camera lens is no longer obscured – see how we’ve remove the upper right corner of ours in the image above. Trim the tabs so the phone’s buttons and headphone socket are accessible. To attach the holder to the bracket with a bolt, first > skyatnightmagazine.com 2013

82 SKILLS NOVEMBER

STEP-BY-STEP GUIDE

Large screens are a boon when taking afocal images of bright targets – like the Moon > drill a small 2mm hole close to the holder’s

centre. Then recess this to prevent the bolt head from scratching your phone: make a 45º countersunk hole in the wood template and line this up with the hole in the holder, then use the centre bit from a lathe and a hammer to widen and recess the hole. Fix a wing nut and bolt through the hole – this will link the holder to the bracket.

STEP 1

STEP 2

Use a saw to cut out the templates to the specifications of your phone and eyepiece. You will need these to mould the finished adapter and bracket. You could also use an old eyepiece body in place of the wooden eyepiece template, if you have one.

Shape the metal to the size of your phone template, leaving some excess to create tabs. Cut out a section so the lens is not obscured. For the bolt to attach the bracket, drill a small 2mm diameter hole, then widen and recess it with a lathe centre and hammer.

STEP 3

STEP 4

Cut a strip of aluminium for the bracket using a hacksaw. Drill a series of holes, then saw or file out the intervening metal so you end up with two slots. These are the adjustment slots to slide the connectors along. Bend the bracket by 90º to finish it.

Take another strip of metal and mould it around the eyepiece template using pliers so it looks like the above. This forms the clasp that attaches to the telescope. Again, consider lining it with felt to help protect the focuser drawtube.

STEP 5

STEP 6

Connect the phone holder and the telescope clasp to the bracket using wing nuts. You can now loosen the screws and slide the adaptor closer or farther away to match the eyepiece on your telescope. Using wing nuts allows you do this without tools.

Place the phone in your adaptor and fasten with strong elastic bands around the top and bottom to prevent it from slipping. If your phone’s headphones have volume adjustment, you can use this as a remote shutter cable to avoid camera shake.

ALL PICTURES: DAVID UTTING

Clasp and bracket For the bracket, take a strip of aluminium and drill a series of holes down its length. Cut or file out the metal between the holes to create two slots – see the image for Step 3. The slot allows you to adjust how the camera lens lines up with different eyepieces. Bend the whole bracket so it is at a right angle. The bracket needs to be long enough to allow the scope clasp to attach below the eyepiece. For the telescope clasp, cut another aluminium strip long enough to fit around your wooden eyepiece template one and a half times – roughly 20x2cm. Drill a hole at each end and one in the middle. Fix a wing nut and bolt through the middle: this will attach to the bracket. Bend the strip around your template with pliers, leaving a triangular space for the bolt head in the middle – see the image for Step 4. The ends of the strip should now run parallel, allowing you to fit a clamping bolt between them and secure the clasp to the focuser drawtube. Assemble the adaptor by connecting the holder to the bracket and the bracket to the clasp – using wing nuts allows you to do this (and adjust the adaptor when observing) without tools. Remove any sharp edges with a file, and line the inside of the clamp and the inside of the holder with felt to prevent scratches. To change eyepieces with the adaptor in place, loosen the wing nut for the telescope clasp and swivel the mount 180 º – we’d recommend securing the phone in the holder with elastic bands before doing this so your phone doesn’t end up on the floor. S David Utting is an amateur astronomer skyatnightmagazine.com 2013

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SKILLS NOVEMBER 85

SKILLS

Sketching NGC 7332 With Carol Lakomiak

NEED TO KNOW STEP 1 Centre NGC 7332 in your eyepiece and use a B pencil to draw the brightest stars in the field. These ‘anchor stars’ are the foundation of your entire sketch, so place them as accurately as possible. A good way do this is by using familiar shapes, like the line and trapezium above.

NAME: NGC 7332 TYPE OF OBJECT: Galaxy CONSTELLATION: Pegasus RA: 22h 37m 24s DEC: +23° 47’ 53” SKETCH: 1-6 November, 6:30 UT till 00:00 UT; 25-30 November, 6:30 UT till 23:00 UT EQUIPMENT: 8-inch reflector; B and H pencils; blending stump FIELD OF VIEW SHOWN: 20 arcminutes; 133x magnification

ALL PICTURES: CAROL LAKOMIAK

L

enticular galaxy NGC 7332 and its companion galaxy NGC 7339 were both discovered by William Herschel in September 1784. NGC 7332 is about one magnitude brighter than its companion, and is located approximately 2º and 6 arcminutes west of mag. +3.9 star Lambda (h) Pegasi. An 8-inch reflector should easily pick up NGC 7332, though whether you are able to detect the companion depends on your sky. To best view the galaxies, you’ll need to use averted vision – a technique where you avert your gaze from your intended target in order to see and sketch it better. You can test the technique by looking at a fairly bright star with the naked eye. Look directly at the star and then slightly to the side of it – see how it seems to get brighter and bloats in size? That’s because your peripheral vision is more sensitive to contrast than your central vision is. The human eye contains cone cells and rod cells, which are activated by different light levels. Cones controlling our colour-detecting central vision are dominant when there’s adequate light.

Rods on the other hand, control our contrast-detecting peripheral vision, and are dominant under low light conditions. You’ll need to use averted vision to detect many of the stars in the field surrounding NGC 7332 – there are only a handful brighter than mag. +13.0. Before drawing the galaxies with the blending stump, mark their locations with a small dot of graphite using the anchor stars drawn in Step 1 as a guide. The centre of NGC 7332 sits between two of the anchor stars and a bit to the west of the line connecting them. The centre of the companion galaxy is halfway between NGC 7332 and the eastern edge of the field. Sketch the galaxies from their centres and work outwards. After you’ve finished the basic shapes, dab on a bit more graphite to represent any brighter regions. Populate the star field using averted vision when needed. As a final step, invert your sketch to a negative image in a photo-editing program. Carol Lakomiak is BBC Sky at Night Magazine’s sketching expert

STEP 2 Draw the galaxies with a blending stump coated with B graphite. Apply the graphite directly to the stump, or make a swatch of graphite on scrap paper and rub the stump across it. Draw the galaxies evenly and with a light touch, and then apply more graphite to indicate brighter areas.

STEP 3 Populate the star field using an H pencil, using the anchor stars from Step 1 as a springboard to help you place them. For example, there’s a delicate chain of stars flowing just below the northern anchor star. Begin with the stars directly below the anchor star and then move outwards.

skyatnightmagazine.com 2013

Astronomy

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SKILLS NOVEMBER 87

SKILLS

Scope

With Steve Richards

DOCTOR

Our resident equipment specialist cures your optical ailments and technical maladies

Some people use webcams with a scope and stack the best frames to create static images. Can I do the same with my DSLR and its video function? I have a Nikon 5100. BENJAMIN WILES

Þ Stacking DSLR videos into still images is

STEVE MARSH, PAUL WHITFIELD X 2

possible, but may require some ingenuity

Webcams have made it much easier to image bright Solar System objects because they capture a large number of image frames that can be stacked using free software such as RegiStax. However, these stacking programs are designed to read the .avi video format and most DSLR cameras output their video data as .mov files. Although there are many software tools available to convert .mov files into .avi files, there are still some issues to resolve concerning the various ‘codecs’ in use. A codec is a piece of

software that compresses video data so that it takes up less space. The codec used to compress the video data must be compatible with the stacking software – this is not always the case. We would recommend either the DIB or YUY2 codec, both of which are compatible with Registax and produce avi files that don’t introduce artefacts. The second issue to resolve is that of file size, as stacking software will work much faster and more reliably using lower resolution images than the ones produced by your DSLR. Another free program called Planetary Imaging PreProcessor (download from http://sites.google. com/site/astropipp) will resolve all of these issues for you. This popular video pre-processing software will not only resize and convert your mov files to avi format with a codec suitable for RegiStax, but it will also allow you to carry out a wide range of other useful pre-processing activities in advance of the actual stacking process.

STEVE’S TOP TIP

ce What types of filter can I use to redu tion? light pollu two different Light pollution can be tackled using filters filter types. Broadband light pollution ciated with asso light attenuate the wavelengths of sodium sure pres low and older mercury vapour and der Baa n, Orio from e ilabl lighting. Ava job at improving Sky-Watcher these do an excellent all view. over the contrast, although they all dim r and luna for lem prob a Luckily this is not such dy alrea are cts obje the as on rvati planetar y obse the ase incre very bright. Another approach is to rve by selecting contrast of objects you wish to obse focus on. An to t wan you the specific wavelengths filter can OIII and owb narr or rast ultra high cont nebulae. like be very effective on emission objects

I’ve just taken my 12-inch Dobsonian out of storage to find that part of the primary mirror has mottled. It’s collimated, but I am unable to bring objects to focus. Please can you advise? ANDREW WELLS

The long-term storage of a reflecting telescope needs to be considered very carefully to ensure that the mirror surfaces don’t degrade over time. Moisture and dust are the enemy here and the varying temperatures experienced in a garage environment can give rise to condensation, which probably explains the mottled finish on your mirror. However, it’s surprising how much detritus and staining a Newtonian telescope’s primary mirror can withstand before the view through the eyepiece deteriorates. From your description, it seems unlikely that this is the cause of your focus issue so a re-collimation should be your starting point. After collimation, use a low-magnification eyepiece to determine if the image gets closer to focus with the focuser racked fully in or fully out. If more outward travel is required, check that you’re using any necessary adaptors, but if more inward travel is required, you may have the wrong adaptor in place. Steve Richards is a keen astro imager and an astronomy equipment expert

Email your queries to [email protected] skyatnightmagazine.com 2013

Quality Astronomy

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REVIEWS NOVEMBER 89

Reviews Bringing you the best in equipment and accessories each month, as reviewed by our team of astro experts

HOW WE RATE Each category is given a mark out of five stars according to how well it performs. The ratings are:

+++++Outstanding +++++Very good +++++Good +++++Average +++++Poor/Avoid

90/98 We examine two offerings from Starlight Xpress: its latest monochrome CCD camera and a five-position filter wheel

N EW SEE INTERACTIVE 360° MODELS OF ALL OUR FIRST LIGHT REVIEWS AT WWW.SKYATNIGHTMAGAZINE.COM

WWW.THESECRETSTUDIO.NET X 4

This month’s reviews

First light

90

Starlight Xpress TriusH814 CCD camera

94

Explore Scientific 9mm 120º eyepiece

98

Starlight Xpress Mini Filter Wheel with OAG

Books

Gear

102

104

We rate four of the latest astronomy titles

Including this 2-inch Crayford-style focuser

Find out more about how we review equipment at www.skyatnightmagazine.com/scoring-categories skyatnightmagazine.com 2013

90

FIRST light

See an interactive 360° model of this camera at www.skyatnightmagazine/360/starxh814

Starlight Xpress

Trius-H814 CCD A low-noise, high-resolution camera with extra USB connectivity built-in

WORDS: STEVE RICHARDS

VITAL STATS s Price £2,475 s Sensor Sony ICX814 (3,380x2,704 pixels) s Well depth/read noise 18,000e/4e-RMS s Size 12.5x10mm, 16.0mm diagonal s Backfocus distance 17mm (±1mm) s Weight 494g s Supplier Starlight Xpress s www.sxccd.com s Tel 0118 402 6898

SKY SAYS… The camera is designed for imaging deep-sky objects at long exposures rather than the Moon or planets

M

anufacturers in the competitive CCD imaging market need to innovate continuously to attract customers. Starlight Xpress has historically led the field so we were keen to examine a CCD camera from its latest Trius range. The Trius-H814 is another in a long line of Starlight Xpress cameras that use Sony CCD sensors, chosen for their low levels of visual noise. All sensors generate noise, both from the process of reading the collected data and from thermal effects as the sensor warms up. Keeping the noise as low as possible produces cleaner images. This 9.2 megapixel camera is the largest of the Sony-equipped mono sensors in the Trius range. With pixels just 3.69x3.69µm in size, the Trius-H814 is ideal for use with short focal length telescopes – when used with our 500mm focal length refractor it produced a high sampling rate of 1.6 arcseconds per pixel. Supplied in a custom-fitted case, the camera is finished in the standard Starlight Xpress gloss black. It has a low-profile, cylindrical body with integral cooling fins, making it suitable for use on a wide range of telescopes including Schmidt-Cassegrains with Fastar capability. Fastar is a device that converts a Schmidt-Cassegrain telescope with a focal ratio of f/10 into a reflector with a much shorter focal length and a focal ratio of around f/2. All the ports are neatly arranged on the rear panel where a pleasant surprise awaits – there are three USB Mini-B ports built-in. There is also a 12V input, an ST4 port and a USB in. A second 12V input can be found on the external fan, which is attached to

the side of the camera. A 12V power supply and a ‘Y’ lead round off the package. The tilt-adjustable front plate of the camera has a female T thread, allowing you to connect a filter wheel, focal reducer, field flattener or coma corrector, or attach a suitably equipped focus tube and a 2-inch nosepiece.

Set-up and shooting We connected the camera to a Starlight Xpress mini filter wheel with a built-in off-axis guider that was attached to a William Optics Focal Reducer and Flattener IV. Various drivers are included on the supplied CD and these installed flawlessly on our Windows 7, 32-bit laptop. However, we had to start each viewing session by plugging in the camera first, then the filter wheel, or else we’d receive a ‘USB error’ message. Also included on the CD was a copy of Starlight Xpress’s SXV-Hmf USB camera control software although for our tests we used MaxIm DL. Our imaging tests were carried out in mid to late August. With the set-point cooling adjusted to –20°C and an ambient temperature of 16.6°C, the camera took three minutes 55 seconds to reach target temperature, and then we were ready to image. Full-size image download time is around five seconds but when focusing, we used 2x2 binning, which made downloads even faster. Binning is a special mode in which several pixels are combined to produce a ‘superpixel’ that is very sensitive to light but reduces the image resolution. The camera is designed for imaging deep-sky objects at long exposures rather than the Moon or >

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The Trius range of cameras have a built-in triple USB hub so that it can be used to control three different devices as well as the camera. One of the major problems encountered in modern deep-sky imaging is the number of cables required to operate and power the all pieces of equipment. Tangled cables are frustrating but with a mount control, camera control, autoguider and filter wheel all vying for

skyatnightmagazine.com 2013

USB sockets, you can also find yourself running out of ports on your computer before everything’s hooked up. Adding an external USB hub into the mix can often be problematic and we hear of connectivity problems using such items, which is why a built-in hub is such a bonus. The Trius-H814 also comes with three short custom cables that connect to the camera at one end and have a female USB connection at the other to plug into your ancillary equipment. The result is a very neat installation.

FIRST LIGHT NOVEMBER 91

ST4 PORT Although the Trius-H814 is designed to be the main imaging camera, it can be used as an autoguiding camera using its built-in, industry-standard ST4 port. However, this opto-isolated (separate circuit) ST4 port can also be used to control your mount through your autoguider when using third-party software like MaxIm DL.

TWO-STAGE PELTIER COOLING A two-stage Peltier cooling system cools the sensor to as low as 40°C below the ambient temperature (a point referred to as the delta T). Set-point cooling selects the delta T and an onboard regulator maintains that temperature. Internal and external fans aid the cooling process.

TILTABLE FRONT Lining the sensor up with your telescope’s optics is vital to avoid distorted stars on one side of the image. The Trius-H814 has a tiltable front plate that works in a similar way to the collimation bolts on the primary mirror of a reflector telescope to adjust its angle.

skyatnightmagazine.com 2013

92 FIRST LIGHT NOVEMBER

FIRST light SKY SAYS… Now add these: 1. Mini Filter Wheel with Off-Axis Guider 2. Starlight Xpress Lodestar Autoguider 3. Starlight Xpress SXV-AO-LF Active Optics

< Globular cluster M13 in Hercules, imaged using LRGB filters

CAMERA CONTROL SOFTWARE The camera control software supplied with the Trius-H814 is a little clunky in comparison with market leaders like MaxIm DL and AstroArt, but it functions well enough and will get you imaging quickly at no additional cost. A perfectly adequate autoguiding feature is included in the software.

WWW.THESECRETSTUDIO.NET, STEVE RICHARDS X 3

> planets. We chose two very different targets to test

out the camera – a globular cluster, M13 in Hercules, and the Eastern Veil Nebula in Cygnus. We found that dark frames (special calibration frames used to remove unwanted noise generated by the sensor) were not required and we were very impressed with the sensitivity of the camera. Despite poor sky conditions during our test period, we captured some satisfying images using both narrowband and LRGB filters. The Trius-H814 is impressive and its highresolution sensor neatly fills the gap between the popular Sony ICX285 and Kodak/Truesense KAF-8300 sensors. We’d recommend the Trius-H814 as an excellent choice for serious mono imaging. S

VERDICT BUILD AND DESIGN CONNECTIVITY EASE OF USE FEATURES IMAGING QUALITY OVERALL skyatnightmagazine.com 2013

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The Eastern Veil Nebula in Cygnus, imaged through a hydrogen-alpha filter

ARGON-FILLED SENSOR CHAMBER The CCD sensor is housed in a sealed chamber, which includes a fused-silica optical glass at the front that is multicoated to reduce reflections and increase light transmission. The sensor chamber is filled with dry argon gas to remove the risk of icing when the cooling system is in full operation.

Welcome to The Tring Astronomy Centre. We are a family run business specialising in Telescopes, Binoculars and a Range of Accessories for both Astronomical and Terrestrial use. We are fully independent so can offer advice based on our many years of being active astronomers. We are official dealers for the following quality brands all of which can be seen in our showroom or purchased online:

94

FIRST light

See an interactive 360° model of this eyepiece at www.skyatnightmagazine/360/exsci9

Explore Scientific

9mm 120° eyepiece A medium-power eyepiece with an astounding field of view WORDS: PETE LAWRENCE

VITAL STATS s Price £758 s Focal length 9mm s Apparent FOV 120° s Eye relief 12.5mm s Optical elements 12, arranged in eight groups s Barrel size 2-inch s Extras eyepiece caps s Weight 0.6kg s Supplier Telescope House s www.telescopehouse. com s Tel 01342 837610

SKY SAYS… The quality of the field is excellent on axis and for a large portion of the main field of view

T

his 9mm, 120° eyepiece is the latest in Explore Scientific’s (ES’s) line of widefield eyepieces. The purpose of a telescope eyepiece is to magnify the image produced by the main telescope optics. The overall magnification is easily calculated by dividing the telescope’s focal length by that of the eyepiece. For example, a telescope with a 1,000mm focal length used with a 10mm eyepiece gives 100x magnification, or power. It’s a good idea to have at least one low-, mediumand high-power eyepiece in your collection. As a general rule, a low-power eyepiece will give a bright, wide field of view, while higher powers show reduced contrast and narrower views. For this reason, higher-power eyepieces tend to be less comfortable to use than lower-power ones. This 9mm eyepiece is ostensibly medium-power, but rather than having the typical restrictive view it offers an immense 120° apparent field of view. The result is an eyepiece that delivers more of an observing experience than a simple vista. It’s important to understand what is meant when referring to a field of view. When you look though an eyepiece, the area of sky you can see depends on the nature of the scope being used. This is the true field of view and gets smaller as a telescope’s focal length increases. The apparent field of view describes how large the view looks to your eye. In the

case of the ES 9mm eyepiece on test, this measures a whopping 120°. Get your eye in the optimal position, 12.5mm from the lens surface, and you can let your gaze roam in all directions around the view. In fact, so wide is this apparent view that you can even look sideways into the eyepiece to take in the extreme edge of the field. The true field of view, or sky area you’re looking at, can be calculated by dividing the apparent field of view by the magnification.

A wealth of sky The first target we observed with this eyepiece was the fabulous Ring Nebula, M57 in Lyra. We’ve seen this object many times before using a 4-inch (918mm focal length) refractor, but this eyepiece really brought it to life. With a magnification of 102x (918mm/9mm), the nebula had a decent size and was quite obvious. But it was the extent of the star field surrounding it that really set the scene, with over 1º of sky to wander your gaze around. M13, the Great Globular Cluster in Hercules, was the next test target. With a large apparent diameter, it looked amazing through the eyepiece. The field was wide enough to show the globular and the two mag. +7.0 stars that flank it in one view. These are 30 arcminutes apart. Many cluster stars can be sharply resolved by carefully focusing the eyepiece. The quality of the field is excellent on axis and for a large portion of the main field of view. Looking at the Double-Double, >

QUITE A SIGHT

WWW.THESECRETSTUDIO.NET X 3

The outstanding views this eyepiece delivers mark it out from the crowd. Constructed from 12 lens elements arranged in eight groups, the eyepiece offers such a wide apparent field of view that your eye can really relax into it – it’s a pleasure to use. In addition, the mediumpower magnification granted by its 9mm focal length still allows you to get in close to your target.

skyatnightmagazine.com 2013

When using it to observe the vast Andromeda Galaxy, M31, through a 4-inch refractor, the view feels like one you’d get using a low-power eyepiece with a much larger scope. One hidden advantage of being able to look around the field of view is that it’s also easier to use the averted vision technique, looking to the side of an object to place its delicate light on a more sensitive part of your retina. Each lens element is multicoated with blackened edges. This results in an exquisite high-contrast view that really is a joy. It’s truly an amazing experience using this eyepiece.

FIRST LIGHT NOVEMBER 95

MOISTURE COUNTERMEASURES The 12 lens elements are housed in a waterproof, fogproof, argon-purged and sealed body. This means that there’s no way for moisture to get inside the eyepiece – whether it’s from natural sources or excessive cleaning. This is a very welcome feature, especially when using the eyepiece outside on cold, damp UK nights.

FILTER THREAD As you’d expect from a premium eyepiece, the barrel is threaded for 2-inch screw-in filters. This means you can attach your favourite filter and continue viewing with the same impressive field of view. Such filters would typically offer enhanced ultra high contrast or even narrowband views of objects such as nebulae.

RUBBER EYECUP The rubber eyecup creates a secure seal around your eye to prevent light seeping in and interfering with your view. It also prevents spectacles from touching the hard body of the eyepiece, which could cause scratches. Placing your eye against the rubber cup with a gentle pressure also positions it for the perfect view.

TAPERED 2-INCH BARREL The double-tapered barrel has two purposes. The first section is designed for easy insertion into a telescope’s eyepiece holder. The second taper, closest to the eyepiece, is precautionary. If the setscrew holding the eyepiece in place becomes loose, this should prevent the eyepiece slipping out and falling to the floor.

skyatnightmagazine.com 2013

96 FIRST LIGHT NOVEMBER

FIRST light

SKY SAYS… Now add these: 1. Orion 2-inch Ultrablock Filter 2. Orion 2-inch Precision Centering Adaptor

FINISH The build quality of the eyepiece is excellent and its body is nicely rounded off with a textured rubberised section around the middle. This section increases grip in cold weather but is subtle enough to allow the eyepiece to keep its attractive, sleek appearance.

3. Lunt 2-inch Solar White Light Herschel Wedge

> Epsilon Lyrae, we had no problem resolving both close pairs of stars at 102x. The resolution and contrast of the eyepiece is fantastic. Some chromatic aberrations did creep towards the extreme edges, but this didn’t detract much from the overall experience.

It’s all about the experience The final observing target was a last quarter Moon. Again, the view was spectacular and it was amazing to be able to see the whole Moon at a reasonable magnification. It’s the sort of view that will have you staying at the eyepiece for a long time to take everything in. One point to consider is that the eyepiece is quite large and heavy, weighing in at 0.6kg – you can see how big it is compared to an average hand at the top of this page. This has the potential to cause balance issues, especially if you’re swapping between eyepieces. Despite that, the ES 9mm, 120° eyepiece is a great piece of kit to add to your telescope. It’s expensive, but the wonderfully wide and comfortable views it delivers will no doubt mean it ends up sitting in your scope’s focuser for long periods, allowing you to really experience your telescope rather than just look through it. S

BUILD AND DESIGN EASE OF USE EXTRAS EYE RELIEF OPTICS OVERALL skyatnightmagazine.com 2013

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98

FIRST light

See an interactive 360° model of this filter wheel at www.skyatnightmagazine/360/starxmini

Starlight Xpress

Mini Filter Wheel with OAG A slim device that changes filters quickly and accurately WORDS: STEVE RICHARDS

VITAL STATS s Price £295 s Backfocus distance 37mm s Filter capacity Five; 1.25-inch s Image camera mounting T thread s Guide camera mounting C thread s Weight 550g s Supplier Starlight Xpress s www.sxccd.com s Tel 0118 402 6898

SKY SAYS… Combining a filter wheel and OAG in a single unit is such an obvious idea, and Starlight Xpress has turned it into an elegant product

M

ono CCD cameras have many advantages over one-shot colour devices, such as DSLRs and colour CCD variants, mainly in terms of sensitivity and versatility. The ability to use a wide range of different filters – both broadband (normal colours) and narrowband (concentrating on very specific wavelengths of light) – has a great deal of appeal. However, swapping filters in and out of the light path by screwing and unscrewing each one in turn quickly becomes a chore. Manually rotated filter wheels holding five or more filters are one solution, but these are neither dust nor light proof, as they normally have an opening to allow you to move the wheel. Automated filter wheels like this one from Starlight Xpress not only allow you to change the filters quickly, but also enclose them in a compartment to provide full protection against dust and light. Starlight Xpress has increased the usefulness of its mini filter wheel even more by incorporating a built-in off-axis guider (OAG). An OAG is one of the two methods of autoguiding with a guide camera; the other is using a second telescope (called a guidescope). Guidescopes are easier to set up and operate, and give a wide selection of potential guide stars, but they often suffer from something called differential flexure. Differential flexure occurs when there’s a small amount of movement between the two scopes, so the imaging scope doesn’t quite follow the guiding corrections

applied to the guidescope. An OAG resolves this issue as the guide camera is coupled so closely to the imaging camera that they both collect light from the same telescope, resulting in better guiding performance. The Starlight Xpress mini filter wheel is built to a high standard and its shiny black finish matches the other CCD-imaging cameras in the Starlight Xpress range. The design ensures that the company’s imaging and guide cameras are parfocal with one another without requiring additional spacers, which makes fitting the filter wheel quick and easy.

Quick change Getting at the filters is a simple task, you just undo four thumbscrews to remove the front plate before unscrewing the single bolt that keeps the carousel on its bearing. Surprisingly, the filters go into the rear of the carousel even though the filter numbers are stamped on its face. It’s a minor issue but it doesn’t make installing them any harder. We would normally adjust the individual focus of the imaging and guide cameras on a new OAG during the daytime by aiming the telescope at a distant object and then focusing both cameras on it. However, we were confident that the Trius-H814 CCD camera (reviewed on page 90) and Lodestar guide camera used for this test would be close to focus as both are made by Starlight Xpress, and we were right. We used a star field in Cygnus to check the focus; the only adjustment >

FITTING INTO TIGHT SPACES

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The industry standard spacing for focal reducers, field flatteners and coma correctors is 55mm (±1mm) from the camera sensor to the mounting face of the corrector. This figure is derived from the nominal sensor to lens-mounting face distance of a typical DSLR camera of 45mm plus the 10mm depth of a typical T adaptor. This is fine for connecting a DSLR camera directly to a corrector but leaves no room for an OAG. This critical spacing problem

skyatnightmagazine.com 2013

becomes even more of an issue for CCD camera users wishing to use both a filter wheel and an OAG. Starlight Xpress has taken this into consideration in the design of its mini filter wheel and OAG as the unit’s total depth is just 37mm. Combined with the nominal 17mm backfocus of the Starlight Xpress range of CCD cameras, this delivers the correct spacing straight out of the box. Competing CCD cameras often have a shorter backfocus, but they too can be used with the mini filter wheel by adding spacer rings.

FIRST LIGHT NOVEMBER 99

GUIDE CAMERA PORT The top of the adjustable prism turret has a heightadjustable collar and a standard C thread around its perimeter to accept any Starlight Xpress guide camera. The vertical movement of the collar allows the guide camera to be focused and a small grub screw allows its orientation to be adjusted.

ADJUSTABLE CAMERA ORIENTATION To ensure that the pick-off prism doesn’t intrude into the light cone falling on the imaging camera’s sensor, it’s important to align the prism with the long edge of the camera’s sensor. This simple slotted adjustment plate with its camera T thread makes setting the correct orientation easy.

skyatnightmagazine.com 2013

100 FIRST LIGHT NOVEMBER

FIRST light

PICK-OFF PRISM This tiny, 45° prism takes a sample of the light that falls outside the light cone reaching the imaging camera and diverts it, via an adjustable turret, to the guide camera. Guide star shapes are slightly distorted but perfectly usable for guiding where just the star’s geometric centre is analysed.

CAROUSEL The carousel holds up to five 1.25-inch filters and is kept in alignment by a plain-nylon bushed bearing running on a brass pillar to produce a secure installation. Drive is applied by a small wheel from underneath, which is held in tension by the sprung drive motor to keep the carousel’s movement smooth.

USB-POWERED MOTOR DRIVE Power comes via the same USB port through which the device receives its control instructions. This convenient method of connection eliminates yet another cable from the usual tangle. The motor inside the device has a beautifully made reduction gearbox.

SKY SAYS… Now add these:

WWW.THESECRETSTUDIO.NET X 2

1. Starlight Xpress Trius-H814 2. Starlight Xpress Lodestar Autoguider 3. Starizona MicroTouch Autofocuser

skyatnightmagazine.com 2013

> we had to make was a small tweak to the focus

collar on the guide camera turret. We had no problems installing the drivers on the supplied CD on our Windows 7, 32-bit laptop. A virtual controller that can select the required filter during an imaging run is included (the Starlight Xpress software can automate this process) but we opted to use MaxIm DL for our test. There’s an option to make filter changes faster by allowing the carousel to rotate in whichever direction brings the required filter into position the quickest, but filter placement was much more accurate with this feature switched off. Using three-second exposures through our William Optics FLT98 refractor gave us a wide choice of guide stars, which made guide-star calibration easy and resulted in excellent guiding.

Combining a filter wheel and OAG in a single unit is such an obvious idea, and Starlight Xpress has turned it into an elegant and cost-effective product. It’s one that should appeal to astrophotographers making the leap from DSLR to long-exposure mono CCD imaging. S

VERDICT BUILD AND DESIGN CONNECTIVITY EASE OF USE FEATURES GUIDING ACCURACY OVERALL

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102

Books New astronomy and space titles reviewed

Dreams of Other Worlds

NASA

Chris Impey and Holly Henry Princeton £24.95 z PB They have been peering through Saturn’s icy rings for nearly a decade, probed the outskirts of the Solar System and supplied us Earthlings with a steady stream of fascinating facts about our corner of space. Spacecraft like NASA’s Cassini and its fellow robotic explorers have visited more corners of our Galaxy than humans will at modern technology, popular culture and any point in the near future. even marine biology. The book is well told, In Dreams of Other Worlds, Chris Impey and interweaves its story with wonderful and Holly Henry chronicle the main little nuggets, for example asking the unmanned space missions of the drivers of two Mars rovers what past 40 years. Intrepid Mars it feels like to control a explorers, the tireless robotic vehicle on another Voyager twins bearing planet. “Probably the greetings from Earth, closest I’ll ever get to Cassini, the Stardust being an astronaut,” probe that hitched a says one. ride on a comet’s tail Not all of the and telescopes eyeing important missions the cosmos at different are listed, though. wavelengths – they all For some reason it transport us to places appears radio telescopes that are as yet impossible are out of favour. There is to visit in person. no mention, for instance, of This book is an Missions like Stardust RadioAstron, a 10m space scope boldly go where none launched by Russia in 2011 that unexpectedly riveting read for of us can – for now a collection of stories featuring integrates with ground telescopes machines rather than, say, astronauts. The to explore black holes and more. Maybe authors do not merely describe the facts the authors could have cut back on the pop of each mission’s launch and key scientific culture references and included a chapter data, but give an interesting account of the on radio astronomy instead. worlds the space projects are travelling to HHHHH or looking at. Along with learning about the conditions on Jupiter’s moon Europa KATIA MOSKVITCH is a science and the cosmic microwave background writer and broadcaster radiation (the fossil light of the Big Bang), readers will find interesting facts about Reader price 17.99, subscriber price 16.99 Earth’s history, Ancient Greek philosophy, P&P £1.99 Code: S1113/3 skyatnightmagazine.com 2013

RATINGS HHHHH Outstanding HHHHH Good HHHHH Average HHHHH Poor HHHHH Avoid You can order these books from our shop by calling 01803 865913

TWO MINUTES WITH CHRIS IMPEY What inspired you to write this book? Space science and astronomy are in a golden age, with new scrutiny on everything from Mars to the distant Universe, so a book on iconic missions that have accelerated our understanding seemed timely. We wanted to convey the excitement of how we are projecting our eyes and ears into space and bringing distant worlds to life. Which mission most excited you? The Hubble Space Telescope is the high watermark. I’ve been lucky enough to use it a dozen times and the data is exquisite. It is the most successful and productive science experiment in history. The images are on thousands of desktops and have penetrated the public consciousness. Some are so bizarre and exotic that it looks like nature could not have been responsible! Remember, in a list of the world’s largest telescopes, it wouldn’t crack the top 50, so it has punched way above its weight. And with astronauts servicing it five times with challenging space walks, it has been rejuvenated to remain state of the art. What do you think will be the next step in unmanned space exploration? For space astronomy, the James Webb Space Telescope is the biggest game in town. It’s taken some heat as the budget ballooned, but it will be by far the largest telescope ever put in space, with nine times Hubble’s collecting area. Ambitious ideas to land on Europa and Titan might get the green light in the next few years, along with space telescopes that can characterise Earth-like exoplanets. CHRIS IMPEY is an astronomer at the University of Arizona

BOOKS NOVEMBER 103

Northern Lights: A Guide Pal Brekke and Fredrik Broms Forlaget Press £34.99 z HB Coffee table-style, large-format books about the Northern Lights tend to be heavy on beautiful photography but light on practical advice for those thinking of heading into colder climes in search of enlightenment. So Brekke and Broms’s careful combination of both – and in a fairly travel-friendly size – is a breath of fresh Arctic air. It’s not all good news, with the authors reporting the depressing facts of Northern Lights viewing that all stargazers will tire of hearing: auroras are unpredictable, so is the (space) weather, so stay for a week, be prepared for –30 º C and whatever you do don’t wear cotton. It’s all so true. At least we have the requisite beautiful photography to take the edge off.

New Stars BOOK for Old OF Marc Read Candy Jar Books £17.99 z HB

TH E MONTH

New Stars For Old brings the history of astronomy to life through a series of 20 highly readable short stories, each of which mixes facts with a good dose of fiction to introduce us to some of the important characters involved. From the Earthcentred theories of Aristotle and Ptolemy through to the visionary genius of Isaac Newton, the basic theme of the book is to outline the often turbulent path taken in the growth and development of the way we think about the Universe. The chapters are a mixture of letters, narrative accounts and diary entries, which collectively remind us that the figures involved are not simply names drawn from textbooks, but were people in their own right.

Exactly when and where to see the Northern Lights is explored. This section is brief, though it does cover the times of year (and times of day) for key sites in Norway, Sweden, Finland and Alaska. There’s also an obligatory section on folklore and art (including several rather pointless photos of the likes of Galileo and Sir Edmond Halley), but overall this is a well-produced book with plenty of detailed information for amateur astronomers. The highlight is a section on observing the different types of aurorae, with detailed advice on photographing the phenomena, including useful hints on what to do about ice and dew. If you do find yourself trapped in a cosy hotel in the Arctic Circle waiting for the skies to clear, this entertaining round-up of all things auroral will put you one step ahead of the spectacle.

HHHH+ JAMIE CARTER is an astronomy tourism and technology writer Reader price 34.99, subscriber price 34.99 P&P £1.99 Code: S1113/4

The text focuses throughout on the interplay between astronomy, astrology and science, as well as offering an insight into the influences of religion and political culture on the way astronomers worked. Other characters, both fictional and real, are brought into the stories. The ‘Notes’ sections that follow each chapter inform us of which characters are real and which are imaginary, and provide historical background to the science. In one of the tales, Johannes Kepler remarks that he followed “where [Tycho] left off, and he picked up from Copernicus who followed Regiomontanus, who relied on Peurbach and all the way back to Ptolemy, no, further, to Callipus and Aristotle, to Eudoxus, to un-named Babylonians.” New Stars for Old tells this story very well and brings history to life in an entertaining and informative way.

HHHHH BRIAN JONES has written 15 books on astronomy and space

Beyond the God Particle Leon Lederman and Christoph Hill Prometheus £19.99 z HB Using a lake full of rainbow trout as a metaphor for a subatomic particle may sound a little strange, but Fermilab particle physicist Leon Lederman and his colleague Christopher Hill make this surprisingly effective linguistic leap in Beyond the God Particle, the sequel to 2006’s The God Particle. Continuing the story of the previous book, Nobel laureate Lederman – who coined the moniker ‘the God particle’ – summarises the advances in physics that made possible the discovery of the Higgs Boson, the elementary particle that gives other particles their mass. He also speculates on how we could probe deeper into the subatomic Universe, and how we could build and use large particle accelerators for this purpose. Moving swiftly from mass to charge, parity, chirality and space-time, the book deftly links together the different concepts and particle interactions that allow our entire Universe as we know it to exist. The tone is conversational and the authors simplify the subject matter well – for example, describing particle accelerators as the world’s biggest microscopes. The first two-thirds of the book are fantastically simple and enjoyable to read. However, the final chunk has a whiff of advertisement, as the authors describe Fermilab’s potential and discuss how the US government should invest in science to maintain the country’s reputation. Still, this book explains the Higgs Boson in impressive clarity and the result is one of the most exciting overviews yet published.

+++++ NICKY GUTTRIDGE is a science journalist and Hubble public information officer Reader price 16.99, subscriber price 15.99 P&P £1.99 Code: S1113/1

Reader price 17.99, subscriber price 17.99 P&P £1.99 Code: S1113/2

skyatnightmagazine.com 2013

104 GEAR NOVEMBER

Gear

Vincent Whiteman rounds up the latest astronomical accessories

1

4 1 FeatherTouch 2-inch Crayford Focuser for Newtonians Price £335 s Supplier First Light Optics 01392 826133 s www.firstlightoptics.com Compatible with a wide range of Newtonian telescopes, this 2-inch focuser offers two drawtube length options as well as coarse and fine focusing adjustment.

2 Heated Gloves Price £9.99 s Supplier Nautalica 01932 235550 s�WWW�NAUTICALIACOM Originally made for North Atlantic fishermen, these heated gloves could spell an end to numb fingers. Power is provided by a single D battery, held in a pouch by the wrist.

5

3 ADM Max-Guider Guidescope Saddle

2

Price £319 s Supplier First Light Optics ��s�WWWlRSTLIGHTOPTICSCOM Saddle up and make fine adjustments to the altitude or azimuth of your finder or guidescope’s position with the Max-Guider. Pointing positions can be locked for long-exposure imaging.

4 Celestron Illuminated RightAngle Correct-Image Finder Price £112.20 s Supplier 365 Astronomy 020 3384 5187 s www.365astronomy.com Compatible with Celestron Schmidt-Cassegrain and Edge HD telescopes, this 9x50 finderscope offers an illuminated crosshair and correctly orientated images.

5 Mid-Weight, Mid-Length Sock

3

Price £30 s Supplier SealSkinz 01553 817 990 s�WWWSEALSKINZCOM Grab a pair of these waterproof socks in preparation for your winter observing sessions. The socks are lined with Merino wool, known for its warmth and moisture control.

6 Take on Mars Price £8.99 s Supplier Take on the Game www.takeonthegame.com Take the helm of a Mars rover and uncover the secrets of the Red Planet on your PC. Complete science missions and fix malfunctions as you cross terrain based on real Martian topography.

skyatnightmagazine.com 2013

6

106 EXPERT INTERVIEW NOVEMBER

WHAT I REALLY WANT TO KNOW IS…

Can black holes affect a galaxy’s size? Chris Done is investigating how the activity at the centre of a galaxy appears to be linked to its overall proportions INTERVIEWED BY PAUL SUTHERLAND

O

bserving a black hole against the black background of space is difficult for the simple reason that light can’t escape it. But we are able to study black holes by the effects they have on their surroundings. When something falls into a black hole, gravitational energy is released. It is similar to the way falling water drives the turbines that generate power in hydroelectric plants, except the energy released by a black hole is enormous. It is enough to heat up the material in the accretion disc swirling around the black hole so it shines incredibly brightly. So brightly, in fact, that it shines not just white hot, but X-ray hot, which means that although you may not be able to see the black hole, you can see the surrounding material in its final moments before disappearing into it. Most of the material falls into the black hole, but a tiny fraction of it can get spat back out in incredibly high-speed jets. Astronomers don’t fully understand why this happens but we think the speed at which a black hole spins might affect the production of these jets.

Most of the material in the accretion disc is doomed, but a small amount is spat out – we see this as a jet

NASA/JPL-CALTECH

Struggles with size There’s a supermassive black hole at the centre of an active galaxy labelled NLS1 PG 1244+026, which lies 500 million lightyears away in Virgo. I was part of a team that measured the speed at which that black hole spins. We were able to do this by using optical and ultraviolet observations to reveal the outer parts of the accretion disc, and X-ray data to show the inner region. We also used the XMM-Newton space telescope to see if we could distinguish the accretion disc from other bits of X-ray emission and learn more about the black hole’s size. Then I thought if we can separate the disc and find out the mass of the black hole we should be able to determine how fast the balck hole spins. There are now fairly well established ways to estimate skyatnightmagazine.com 2013

ABOUT CHRIS DONE

Prof Chris Done of Durham University sets her head spinning by checking out the mass and rotation speeds of supermassive black holes that power quasars and active galactic nuclei.

mass, and in PG 1244+026 we can separate out the disc component, so we had everything we needed. Our observations of this black hole indicate that its event horizon isn’t spinning anything like as fast as it could. It most probably rotates at less than half the speed of light, which is considered slow. That tells us the black hole grew its mass in lots of little bits – by snacking, rather than enjoying one big meal that would have spun it up to maximum speed. Material came in and tried to spin the black hole in one direction, before more material entering from another direction tried to spin it another way. This a clue to the structure of the gas close to the black hole and it suggests the black hole probably gets that gas from starformation events nearby. Material is carried by stellar winds or from events such as supernovae, and the material that gets drawn into the black hole affects how it spins. Oddly, there also seems to be a large-scale connection between the mass of the black hole and its surroundings. The size of the black hole appears to be linked to the size of the galaxy, which is rather like saying the size of a car relates to the size of the Earth. But, somehow, something about the black hole and the accretion flow into it can affect the galaxy on huge scales. This might be where those jets come in. Perhaps a jet transports a lot of that accretion power from around the black hole to areas far away, and so is able to heat gas and control star formation in the galaxy as a whole. Unfortunately, we don’t understand the connection between the jets and a black hole’s spin. The supermassive black hole in NLS1 PG1244+026 has a low spin, suggesting it may not have dramatically powerful jets, and yet somehow its size ‘knows’ about the galaxy. We plan to follow up by checking other galaxies with distinct accretion discs. I’ve already found one that has a very powerful radio jet and a high-spin speed, so I’m very excited. S

SOUTHERN HEMISPHERE IN NOVEMBER With Glenn Dawes > 1 November 00:00 > 15 November 23:00 > 30 November 22:00

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The chart accurately matches the sky on the dates and times shown. The sky is different at other times as stars crossing it set four minutes earlier each night. We’ve drawn the chart for latitude –35° south.

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Although the Milky Way hugs the horizon during the evenings, there is still plenty to see. Watching the Teapot asterism in Sagittarius diving spout-first towards the western horizon is a reminder of the passing of the winter months. Low in the east is Orion, the Hunter, and its three distinctive belt stars – which double as the base of the Saucepan asterism. Nearby, mag. –1.5 Sirius (Alpha (_) Canis Majoris), the brightest star in the sky, betrays the location of one of Orion’s hunting dogs.

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Comet C/2012 S1 ISON may be impressive in the late morning sky; even if it puts on a poor show it should be a good binocular object. The comet will only be visible up until perihelion in late November. It begins the month in Leo, 7° to the lower left of Mars; on the 18th it is 1° from mag. +1.0 star Spica (Alpha (_) Virginis). Thereafter the comet drops quickly towards the Sun and becomes a dawn-only object. Depending on its brightness it may be still visible on 24th, forming a triangle with Mercury and Saturn.

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around 02:00 EST, can be viewed in the pre-dawn eastern sky. Dawn sees Mercury make a brief appearance, but it remains low and in the Sun’s glare. Also rising out of the eastern glow is Saturn, which passes just 0.5º from Mercury on the 26th.

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You can’t miss Venus in the early western evening sky as it passes across the Teapot asterism. Uranus and Neptune are also well placed in the early evening. Jupiter rises before midnight, but is best observed in the morning. Mars, arriving at

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2.5 arcseconds apart; up the magnification if its duality isn’t obvious at first.

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The constellation of Phoenix is known for its faint galaxies. NGC 625 (RA 1h 35m, dec. –41° 26’), pictured, is the exception. This edge-on spiral, just 2.2° northeast of mag. +3.4 star Gamma (a) Phoenicis, has a bright central region measuring 2 arcminutes by 0.5 arcminutes.

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skyatnightmagazine.com 2013

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SOUTH skyatnightmagazine.com 2013