CATCH JUPITER AT ITS BEST: WE SHOW YOU HOW
Sky at Night THE BIGGEST NAME IN ASTRONOMY
ON … SEE THEM THIS SEAS
10 WONDERS WINTER
’S THE WORLD ST E B & BIGGEST
NIGHT-SKY GUIDE
From spectacular nebulae to glittering star clusters, don’t miss these stunning sights PLUS
Apollo 17: the 40th anniversary
Relive humankind’s final footsteps on the Moon
ALSO IN THIS ISSUE
The light of Martian life
Reflected sunlight may hold biological markers
The stellar store cupboard
THE BIG QUESTIONS How do we know the shape of empty space?
A new ingredient in the star formation recipe? The Christmas survival guide
HD controller: the new Vixen Go-To mount on test
Make a collimator from household items DECEMBER 2012 #91 www.skyatnightmagazine.com
LETTER FROM THE EDITOR DECEMBER 03
Welcome
This month’s contributors include...
Your indispensable Christmas companion, whatever the weather
PETE LAWRENCE SKY AT NIGHT REPORTER
With Jupiter at opposition this month, Pete takes a timely look at how to de-rotate images, create animations and more on page 69.
KENDRICK OLIVER SPACE RACE HISTORIAN
Forty years after the last Apollo mission, Kendrick looks at how space travel changed the lives of the astronauts themselves. MARK PARRISH TELESCOPE MAKER
Handyman Mark shows you how to put together a simple collimator using items from around the home on page 82. HAZEL MUIR
SCIENCE WRITER
Hazel delivers the latest astro news on page 13, including the discovery of an exoplanet in the star system nearest to us.
This month is the 40th anniversary of Apollo 17. On 7 December, the last manned mission to the Moon launched on the 12-day, 700,000km roundtrip to lunar orbit and back again. It was the final chapter in a heroic era that inspired a generation and continues to fascinate those born since those exciting times. Read more about the mission on page 40. If you’re in need of inspiration this winter there’s no shortage of stunning objects to view this month in the skies above. Turn to page 32 for our top celestial choices; sparkling star clusters, planetary alignments and the chance of catching a Geminid meteor or an auroral storm await. If the skies conspire against us over the Christmas break, and you need a diversion this festive season, we have just the thing on page 44. Here you’ll find a survival guide full of ideas for an astronomy boost should visiting relatives and leaden skies threaten your sanity. Clear skies and seasons greetings! Chris Bramley Editor
PS Next issue goes on sale 18 December.
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The 150 Greatest Photographs of the Universe Our latest collector’s issue is on sale now. In The 150 Greatest Photographs of the Universe, we’ve selected our favourite professional images of space to create a stunning pictorial journey from the planets of the Solar System to the most distant galaxies, taking in such sights as wonderful Saturn and glowing supernova remnants. Buy it from WHSmith or online at www.buysubscriptions.com: http://bit.ly/great_photo
Sky at Night LOTS OF WAYS TO ENJOY THE NIGHT SKY...
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In the magazine ON THE COVER 32 69
44
40 18 16 77 94
82
COVER IMAGES: DAVID NUNUK/SCIENCE PHOTO LIBRARY, GRAHAM GREEN, PLEIADES: THINKSTOCK
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WINTER WONDERS Cold nights are a given, but these sights are worth wrapping up for
FEATURES
REGULARS
06 Eye on the sky
13 Bulletin
32 Winter wonders
Ten of our experts share their favourite winter objects – we tell you how to see them.
40 Apollo 17
Our final Apollo retrospective bids farewell to the last men to set foot on the Moon.
44 The Christmas survival guide
All the gear and gadgets you need to make it through a cloud-covered festive season.
64 The spirit of Apollo
Find out why astronauts came back to Earth with a fresh view on our place in the cosmos.
69 Working with WinJUPOS
Four projects to help you improve your planetary images using this free software.
77 The big questions
This month: how can space be curved? skyatnightmagazine.com 2012
The latest astronomy and space news.
20 Interactive
Your letters, emails and tweets.
82 How to…
Make a collimator for your Newtonian reflector using household items.
85 Scope doctor
Your astro equipment questions answered.
24 SUBSCRIBE Get your issues at a discount
86 What’s on
Astronomy events from around the UK.
89 Reviews
26 Hotshots
The finest of your astro images, sent in from all over the world.
47 THE SKY IN DECEMBER Your 15-page guide to the night sky featuring our pick of the top sights, an all-sky chart, a deepsky tour and much more…
First light 90 Officina Stellare RH-200 8-inch astrograph.
94 Vixen Sphinx Pro equatorial Go-To mount.
98 Orion StarShoot G3 monochrome CCD camera.
102 Books This month’s essential astronomy titles.
104 Gear The best stargazing accessories.
106 What I really want to know is…
How can we analyse ancient galaxies?
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Time travelling
telescope Hubble looks back to when the Universe was 25 times younger than it is today HUBBLE SPACE TELESCOPE 25 SEPTEMBER 2012
SANTA CRUZ), R BOUWENS (LEIDEN UNIVERSITY), AND THE HUDF09 TEAM
NASA, ESA, G ILLINGWORTH, D MAGEE, AND P OESCH (UNIVERSITY OF CALIFORNIA,
This incredibly detailed composite image from the Hubble Space Telescope is the deepest ever view of the Universe, capturing ancient galaxies up to 13.2 billion years old. Called the eXtreme Deep Field (XDF), this ground-breaking picture was assembled using 10 years of photographs of a patch of sky at the centre of the Hubble Ultra Deep Field, a small region of space in the constellation of Fornax. The XDF contains many different types of galaxy, from spirals like our own Milky Way to red fuzzy galaxies, left barren and devoid of their star-forming capabilities after cataclysmic galactic collisions. The image shows around 5,500 star systems in total, the faintest of which are just one 10-billionth of the brightness that the human eye can see.
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NASA/JPL/UNIVERSITY OF ARIZONA, ESO, NASA/JPL-CALTECH/SPACE SCIENCE INSTITUTE, NASA
Rock of ages MARS RECONNAISSANCE ORBITER 26 SEPTEMBER 2012 The undulating detail of Luki Crater in Mars’s southern highlands has been captured by the Mars Reconnaissance Orbiter’s HiRise camera. The diversity of colour in the image is evidence of a wide variety of rock types.
Glittering gull EUROPEAN SOUTHERN OBSERVATORY 26 SEPTEMBER 2012 The young star HD 53367 glows energetically, illuminating the heart of the Seagull Nebula in this vibrant image taken by the Wide Field Imager on the MPG/ESO 2.2m Telescope. The cloud of dust and gas lies 3,700 lightyears away.
skyatnightmagazine.com 2012
EYE ON THE SKY DECEMBER 09
Saturnian spider legs CASSINI SPACECRAFT, 1 OCTOBER 2012 NASA’s Cassini spacecraft has revealed a spider-like ray crater on Saturn’s moon Dione in this image, taken from a distance of 418,000km. Visible in the upper-left of the shot, bright white ejecta rays can be seen spreading from the impact crater.
Spitting fire SOLAR DYNAMICS OBSERVATORY 31 AUGUST 2012 A well-defined magnetic filament explodes from the Sun in this energetic image, captured in extreme ultraviolet light by NASA’s Solar Dynamics Observatory. Ignited by a solar flare, this long filament was eventually stretched to breaking point – some of its displaced particles reached Earth’s atmosphere, creating a dramatic auroral display.
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10 EYE ON THE SKY DECEMBER
Hooke shot MARS EXPRESS 4 OCTOBER 2012 The High Resolution Stereo Camera on ESA’s Mars Express has revealed diverse geographical features in and around Hooke Crater. Half of the crater can be seen in this image, with dunes clearly visible at its centre. To its left is the Argyre Planitia; a thin layer of frozen carbon dioxide gives it a silvery appearance.
Sharpened pencil
ESA/DLR/FU BERLIN (G. NEUKUM), ESO
EUROPEAN SOUTHERN OBSERVATORY 12 SEPTEMBER 2012 The Wide Field Imager on the MPG/ESO 2.2m Telescope has captured the aptly named Pencil Nebula in superb detail. This elongated cloud of glowing gas is part of a much larger supernova remnant, the leftovers of a stellar explosion that took place some 11,000 years ago.
skyatnightmagazine.com 2012
BULLETIN DECEMBER 13
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
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The tantalisingly close exoplanet may be Earth mass, but it’s unlikely that it could support life as we know it
Comment
by Chris Lintott
Planet found in Alpha Centauri system
ESO/L. CALÇADA/NICK RISINGER
Scientists uncover a world in the nearest star system to the Sun ASTRONOMERS HAVE DISCOVERED a planet with a mass roughly the same as Earth in the nearest star system to the Sun, Alpha Centauri. The planet is so close to its star it’s likely to be too hot to be habitable. “We live in exciting times,” says Xavier Dumusque from the Geneva Observatory in Switzerland, who led the team that made the discovery. “This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun.”
Alpha Centauri lies only 4.3 lightyears away. It’s a triple star system consisting of two stars similar to the Sun, Alpha Centauri A and B, and a fainter red companion called Proxima Centauri. The planet has been found orbiting Alpha Centauri B. Using the La Silla Observatory in Chile, the team measured a slight ‘wobble’ of Alpha Centauri B due to the gravity of a planet orbiting around it. The measurement was amazingly sensitive – the star’s wobble speed is only around 50cm per second. The analysis suggests that a planet orbits Alpha Centauri B every 3.2 days, and that it is much closer to the star than Mercury is to the Sun. “This is the first planet with a mass similar to Earth ever found around a star like the Sun,” says team member Stéphane Udry, also from the Geneva Observatory. “It must be much too hot for life as we know it.” > See Comment, right
Prominent exoplanet researcher Geoff Marcy at the University of California, Berkeley, has been pushing for a simple interstellar probe to be launched as soon as possible; with this discovery he now has a target to aim for. But how realistic is a trip to our new nearest neighbour? The fastest spacecraft headed out of the Solar System, Voyager 1, would take 70,000 years to complete the 4.3-lightyear trip. But plans for suitable technology do exist – solar sails and advanced ion drives, which build on those pioneered by ESA’s SMART-1 lunar mission in the early 2000s, might get us there in hundreds of years. Such a probe would be cheap to build and could send us back pictures of an alien solar system. It would reveal Alpha Centauri’s worlds just as Voyager taught us about the outer planets in our own Solar System. Simply knowing that we were on our way would surely be inspiring – even if we won’t be here to see what it finds. CHRIS LINTOTT co-presents The Sky at Night on BBC TV
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Hot gas enshrouds the Milky Way The gaseous cocoon could explain some ‘missing matter’
News in brief WATER, WATER EVERYWHERE
ILLUSTRATION: NASA/CXC/M.WEISS/NASA/CXC/OHIO STATE/A GUPTA ET AL, ESA/ MPS, KATLENBURG-LINDAU, GERMANY, JHUAPL/SWRI, NASA/JPL-CALTECH/ASI, NASA/ESA/W. ZHENG (JHU)/M. POSTMAN (STSCI)/AND THE CLASH TEAM
ESA’s Herschel Space Observatory has revealed vast amounts of water vapour in a cloud of gas and dust that’s on the verge of collapsing to form a new star. Astronomers say the water vapour is enough to fill Earth’s oceans 2,000 times. The cloud, known as Lynds 1544, lies in the constellation of Taurus. “To produce that amount of vapour, there must be a lot of water-ice in the cloud,” says team leader Paola Caselli from the University of Leeds.
ASTEROID 4 VESTA HOSTED DYNAMO
The gas halo is so large it may encompass other members of the Local Group
NASA’S CHANDRA X-RAY Observatory has revealed that the Milky Way is embedded in an enormous halo of hot gas that extends for hundreds of thousands of lightyears. Astronomers estimate that the halo’s mass is roughly the same as the mass of all the stars in our Galaxy’s disc, thought to be several billion times the mass of the Sun in total. “The Chandra observations imply a huge reservoir of hot gas around the Milky Way,” says team member Smita Mathur from Ohio State University in Columbus. “It may extend for a few hundred thousand lightyears farther into the surrounding Local Group of galaxies. Either way, its mass appears to be very large.” Astronomers already knew that the Milky Way, and other galaxies, are embedded in warm gas that’s at least 100,000 ºC, as well as hotter gas with temperatures greater than 1 million ºC. To find out how much hot gas surrounds the Milky Way, Mathur and her colleagues used Chandra to measure how much light the gas absorbs from eight bright X-ray sources far beyond our Galaxy. skyatnightmagazine.com 2012
The results suggest the temperature of the hottest gas is up to 2.5 million ºC – much hotter than the surface of the Sun. Combining the Chandra data with observations by ESA’s XMMNewton satellite and Japan’s Suzaku satellite, the team concludes that the mass of the hot gas is equivalent to that of 10 to 60 billion Suns. The finding could resolve an astronomical puzzle that has persisted for more than a decade. Observations of very distant galaxies suggest that normal matter, made of atoms, represented about one-sixth of the mass in the Universe when it was only a few billion years old, the rest being invisible dark matter, which remains unidentified to this day. However, modern observations of stars and gas in our local part of the Universe had suggested that about half of the normal matter was unaccounted for. Mathur and her colleagues say the missing normal matter could have been hiding in the hot gas that envelopes our Galaxy, and presumably other galaxies as well. www.nasa.gov/chandra
Scientists at the Massachusetts Institute of Technology have found evidence for a dynamo-driven magnetic field in an asteroid for the first time. Earth generates its magnetic field due to a dynamo, a molten, swirling mass of conducting fluid in its core. Researchers who studied a meteorite from the large asteroid 4 Vesta have concluded that it once had a long-lived magnetic field, driven by the same mechanism, when it was less than 100 million years old. “4 Vesta now becomes the smallest known planetary object to have generated a dynamo,” says team member and professor of planetary science Benjamin Weiss.
BULLETIN DECEMBER 15
VENUS’S ATMOSPHERE FEELS THE COLD VENUS IS RENOWNED for its oven-hot surface and scorching carbon dioxide atmosphere, but ESA’s Venus Express spacecraft has discovered a curiously cold region in the planet’s upper atmosphere at an altitude of about 125km. The cold layer lies at the terminator, the dividing line between the planet’s day and night sides. With a frigid temperature of around –175°C, it is chillier than any part of the Earth’s atmosphere. It may be cold enough for carbon dioxide to freeze and fall as ice or snow. Scientists have not yet found a clear explanation for the cold layer, which rests between two warmer zones. “The finding is very new and we still need to think about and understand what the implications will be,” says Håkan Svedhem, project scientist for Venus Express. www.esa.int/venusexpress
The unexpected cold layer exists around the terminator
News in brief ‘HOT CROSS BUN’ FOUND ON TITAN
NASA’s Cassini spacecraft has revealed a strange feature, below, on Saturn’s moon Titan that looks like a huge hot cross bun. It may have formed due to hot magma pushing the surface up from below, just as steam rising in baking bread can lift and crack its surface. “It is a type of feature we haven’t seen before on Titan,” says Rosaly Lopes from NASA’s Jet Propulsion Laboratory in California. “Titan keeps surprising us even after eight years of Cassini observations.”
Debris threatens Pluto mission The New Horizons probe may have to steer clear of the dwarf planet Scientists won’t know how much risk there is to the New Horizons probe until it’s nearly at Pluto
NASA’S NEW HORIZONS spacecraft, currently en route to Pluto, may have to change its planned trajectory past the dwarf planet. Scientists have become increasingly concerned that it might be damaged by debris orbiting the Pluto system. In July 2015, New Horizons will make its closest approach to Pluto, which has turned out to have several moons. “We’ve found more and more moons orbiting near Pluto – the count is now up to five,” says Alan Stern, lead scientist for the mission.
ULTRA-DISTANT GALAXY SPOTTED
Collisions between these moons and smaller bodies probably generate debris fragments. And because the spacecraft is travelling at about 50,000km/h, it could be disabled if it hits a fragment smaller than a pebble. The team will use every available tool, including the Hubble Space Telescope, to search for debris, but it may be necessary to change course. “We may not know whether to fire our engines and bail out to safer distances until just 10 days before reaching Pluto,” says Stern. “This may be a bit of a cliffhanger.” www.nasa.gov/newhorizons
A contender for the most distant galaxy ever seen has turned up in observations by NASA’s Spitzer and Hubble Space Telescopes. Astronomers estimate that the galaxy is so distant that its light took 13.2 billion years to reach Earth. It’s circled in the image below, appearing as a very faint red speck. The observed starlight left the galaxy when the Universe was only 500 million years old. “This galaxy is the most distant object we have observed with high confidence,” says team leader Wei Zheng from the Johns Hopkins University in Maryland.
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CUTTING EDGE
Our experts examine the hottest new research
Stirring up the recipe for making stars Astronomers may need to rethink their ideas about the ingredients needed for star formation WORDS: CHRIS LINTOTT The processes going on in star-forming regions like NGC 3603 may not be as clear cut as previously thought
needs to be present for it to form in large quantities. Carbon and silicon are forged in stars, so we’ve long thought that the first stars must have been unusual – devoid of these elements. With only hydrogen and helium to hand, only the largest clumps of gas would have been able to cool enough to collapse to form stars. Once they’d been and gone, producing metals in the process, we thought we were safe in explaining
ESO
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hat’s the recipe for making a star? Astronomers thought they had it nailed down, but a paper from American astronomer Mark Krumholz suggests that, in the right circumstances, the ingredients list may need a little rewriting. The traditional recipe goes like this: take a large clump of gas and dust, preferably enriched with a sprinkling of the elements astronomers call ‘metals’ – all the ones heavier than hydrogen and helium. Hide the gas within the dust cloud to protect it from the harsh glare of interstellar space and allow to cool for a few million years to a temperature of just above absolute zero (–273ºC), until the gas cloud inevitably collapses under its own gravity, leading to the start of nuclear reactions. The critical step is the cooling of the gas. Think of temperature as nothing more than a measure of the speed the gas molecules are moving at: if it’s too high the random motion will prevent gravity’s attempt to make the cloud collapse. But cooling something to such low temperatures is not easy. Protostellar material manages it through the behaviour of the molecules it contains: molecular hydrogen and carbon monoxide shine in the microwave region of the spectrum, and by doing so they transmit energy away from the cloud. So no molecular gas, no star formation. Molecules in protostellar material contain ‘metallic’ elements, most commonly carbon, oxygen or nitrogen, so the presence of at least a drizzle of heavier elements is clearly crucial for making them. Even the simplest of molecules, molecular hydrogen, forms on the surface of dust grains, which means silicon or carbon skyatnightmagazine.com 2012
“A lot of work assumed that star formation is impossible in the absence of molecular gas. That looks to be unfounded”
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
star formation with the aforementioned recipe. But Krumholz’s paper convincingly shows that there are places in the Universe where something else happens. When the amount of metals available is only a few per cent of that in the vicinity of the Sun – in some dwarf galaxies, for example – atomic gas can take on the role normally played by molecular gas. Atoms can emit radiation too, and in these special places it seems that radiation from carbon can cool gas faster than molecules can assemble, allowing stars to form. It seems like a relatively trivial change – no different to a little improvisation when faced with a bare store cupboard – but there are important implications. A lot of theoretical work has assumed that star formation is impossible in the absence of molecular gas, an assumption that now looks completely unfounded. Perhaps we should have read the whole recipe carefully before starting, instead of rushing into the kitchen.
CHRIS LINTOTT was reading… Star Formation in Atomic Gas by Mark Krumholz. Read it online at http://arxiv.org/abs/1208.1504
BULLETIN DECEMBER 17
News in brief
Amateur breaks supernova records
The yellow crosshairs mark Boles’s 150th supernova; inset, the man himself
His latest find in Perseus caps off 15 years of discoveries
HAVEN GIGUERE/YALE, GETTY, GEORGE FAIRBURN, TOM BOLES, NASA/JPL-CALTECH/MSSS, NASA
Citizen scientists have helped discover the first planet in a four-star system. Volunteers spotted the world while sifting through images on www.planethunters.org, a website that invites the public to look for signs of planets passing in front of stars using data from NASA’s Kepler spacecraft. Professional astronomers confirmed the discovery and showed that the newly discovered planet orbits twin stars, which are in turn orbited by a second distant pair of stars. The planet is a gas giant that’s slightly bigger than Neptune. “This unique system might have been entirely missed if not for the sharp eyes of the public,” says Debra Fischer, a professor of astronomy at Yale University who helped launch Planet Hunters.
MONEY’S TIRELESS WORK REWARDED
Sky at Night Magazine’s reviews editor, Paul Money, has been awarded the Sir Arthur Clarke Lifetime Achievement Award. Judges praised his tireless work to promote astronomy and Paul was “both surprised and honoured” to receive the award.
Boles spotted his 150th supernova in a faint galaxy in the constellation of Perseus. It’s likely to have occurred when a very massive star ran out of fuel and its core violently collapsed.
MARS WEATHER EXCITES ASTRONOMERS
It looks balmy now, but Mars gets as cold as –70ºC at night
Looking back
A PLANET WITH FOUR PARENTS
IN AUGUST, AMATEUR astronomer Tom Boles discovered his 150th supernova from his self-built private observatory in Coddenham, Suffolk. That’s the largest number of supernovae found by any individual. “This is another milestone for the observatory; 29 October was the 15th anniversary of my first discovery,” says Boles. “I had no idea when I started that I would continue for so long or make this many discoveries.”
NASA’S ROVER CURIOSITY has experienced unexpectedly mild weather on the Red Planet’s surface. Average daytime air temperatures have reached 6º C, even before the Martian summer starts. “That we are seeing temperatures this warm already during the day is a surprise,” says Felipe Gómez from the Centre for Astrobiology in Madrid, Spain. “If this warm trend carries on into summer, we might even be able to foresee temperatures in the 20s – that would be really exciting from a habitability point of view.” www.nasa.gov/msl
The Sky at Night December 1982 On 5 December 1982, The Sky at Night broadcast featured the last man on the Moon, Eugene Cernan, who left the lunar surface 10 years earlier in December 1972. Cernan was the commander of Apollo 17, the final mission of the Apollo program. No-one has walked on the Moon since.
d Cernan reache /h km 18 a record ver in the lunar ro
A former US Navy officer, Cernan participated in NASA’s Gemini and Apollo programmes from 1963. During the Apollo 17 mission, he and fellow astronaut Harrison Schmitt explored the Moon for around 22 hours, covering a distance of more than 35km using a lunar rover. Cernan attained a lunar speed record, driving the rover at 18km/h, and
appeared on The Sky at Night again in 2007, the year the programme celebrated its 50th anniversary. You can also read all about Apollo 17 in our 40th anniversary feature on page 40.
skyatnightmagazine.com 2012
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CUTTING EDGE
Our experts examine the hottest new research
Life may have marked light from Mars A simple quirk of nature may allow scientists to identify the signs of ancient life WORDS: LEWIS DARTNELL Light bouncing off the Red Planet could hold the answer to the riddle of life on Mars
which measures both the spread of wavelengths and polarisation in light, is a common tool in chemical analysis and is widespread in astronomy. This raises a question: can we use telescopic observations to detect polarisation caused by homochiral (and thus probably biological) compounds in light reflected off other worlds? This is what Sparks and his team have been working on. Chlorophyll imparts an exceptionally strong
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uch of the motivation for exploring the Solar System lies in the prospect of finding the signs of life beyond Earth, something that’s been strengthened by NASA’s Curiosity rover landing on Mars. One way to do this is to look for the telltale quirks biology leaves in organic compounds. A good target, says William Sparks of the Space Telescope Science Institute in this new paper, is chlorophyll, the green pigment that allows plants, algae and cyanobacteria to photosynthesise. Many organic molecules can exist in two forms, mirror images of each other, known as ‘enantiomers’. This is analogous to your left and right hands – they’re essentially identical forms, but cannot be rotated to match one another. One of the central features of all life on Earth is that it uses one of the two enantiomers: all sugar molecules are the right-handed variant whereas all amino acids in proteins are left-handed. It’s not entirely clear why one mirror-image molecule was chosen over its counterpart, but when it was the selection was locked in: the enzymes of life can only operate on one form or the other, not both. We can test whether organic residue on Earth is biological by checking whether it is made up of all the same enantiomers – whether it is ‘homochiral’ or not. Likewise, we’d be pretty confident of having detected signs of past life on another world if we found carbon-based compounds that are also strongly biased in their make-up of enantiomers. One feature of a homochiral sample of only one enantiomer is that any light that passes through or reflects off it becomes polarised (orientated) in a certain way. For this reason spectropolarimetry, skyatnightmagazine.com 2012
“One way to search for life on other worlds is to look for the telltale quirks biology leaves in organic compounds”
Lewis Dartnell is an astrobiologist at University College London and the author of Life In The Universe: A Beginner’s Guide
polarisation signal in light reflected from it, clearly distinct from any background rock minerals. Even small clusters of photosynthetic bacteria on a rock would yield a subtle overall polarisation effect. Sparks is confident that we could detect the polarisation with current technology and has confirmed that there is no background polarisation coming from Mars’s surface that might mask the signal. He proposes that a spectropolarimetry instrument be included on a future Mars orbiter mission to survey the ground beneath for this elusive signature of past microbial life. Finding evidence of long-dead life on Mars in this way may be a long-shot, but I suspect that such an instrument could also assess the prevalence of photosynthetic bacteria in hostile environments on Earth, such as the polar ice sheets: crucial unexplored territory on our own planet.
LEWIS DARTNELL was reading… Remote Sensing of Chiral Signatures on Mars by William Sparks et al. Read it online at http://arxiv.org/abs/1209.0671
Merry Christmas from
With special guests Chris Lintott, Pete Lawrence and Paul Abel from the BBC’s Sky at Night TV programme Also starring:
With over 40 trade stands, exciting live demonstrations and much, much more, you can’t afford to miss it! Buy your tickets on-line now. See our website for details: The perfect gift to put under the tree at Christmas!
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Interactive
EMAILS • LETTERS • FORUM • TWEETS • CROSSWORD
This month’s Email us at
[email protected] top prize: four Philip’s books MESSAGE OF THE MONTH 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 Stars and Planets. Stargazing with Binoculars by Robin Scagell and David Frydman contains equipment and observing guides, and you’ll be viewing planets in no time with Peter Grego’s Solar System Observer’s Guide.
Trooping the colours
I have been reading your excellent magazine for many years and have picked up many good observing tips, but I just have to congratulate Paul Abel on his superb article about planetary filters. It is very informative and allows us to buy only the filters suited to our own viewing habits. After reading the feature, I dusted off my own filters and tried them out on Jupiter. Paul is right, the
Our number’s up With the deep-sky tour map in the magazine (and the printout on coverdisc), I have trouble with the printed numbers that mark each item – they tend to blend in to the rest of the chart (more so in red light). I wonder if this solution would enhance it for everyone: if the numbers were outline type then they would be much easier to spot on the map compared to the grey numbers. Keep up the great work on the mag. Trevor McKay, Northern Ireland
A useful suggestion, Trevor, we’ve tested it and it really works. From this issue on, the numbers on the deep-sky tour map will be outlines. – Ed
It’s all in the balance Your feature Tour the Milky Way in issue 88 (page 32) moves me to offer some constructive criticism of a magazine I enjoy and read from cover to cover. Its 10 objects are so low in the sky that even if your horizon is sufficiently clear, any light pollution will flood them out. If you are anywhere north of the M25 you really have very little chance of seeing them unless you find some convenient dark hill. Astronomers are eternal optimists. Given the skyatnightmagazine.com 2012
red filter enhances the cloud belts and helps pick out the Great Red Spot. I also tried a light pollution filter, which reduced the glare and increased the contrast, and just for a giggle I tried a ultra high-contrast planetary nebula filter, which gave a colourful and surprising result. Sometimes reading your magazine, I get the impression I am one of the few astronomers not doing astrophotography, but each to his own. John Twaites, via email
Always nice to know an article is useful. Fear not on the visual observer front: you’re not alone. There are still a few of us left to spread the message! – Paul Abel
weather conditions in the UK and much of western Europe they have to be. But we also have to be realistic and while I understand the desire to push the boundaries, and look at more and more fascinating objects, I think that at times we are in danger of going too far. The ‘sensible’ option is to set up in your back garden and see what you can see from there. Colin Miles, via email
Back garden observing is the norm, Colin, and there’s always plenty of targets suggested in the Sky Guide. Once in a while, though, nothing beats observing somewhere truly dark, when features like this come in useful! – Ed
A spectacular flyover To celebrate our 10th wedding anniversary my wife Sarah-Jane, our two small children Louis (four) and Holly (20 months), and myself spent a week in Paris. The City of Lights is not perhaps the best location to image the night sky, but I had optimistically hidden my camera tripod among a bag of nappies and toys while my wife was distracted by a graffiti incident involving a small child, a crayon and the living-room wall. Despite the high level of light pollution it was possible to identify some of the
LETTERS DECEMBER 21
The big debate Have your say at http://twitter.com/ skyatnightmag @skyatnightmag asked: A lot happened in the world of astronomy during 2012, but which event was most memorable for you? @astrogirl3011 Can we have the two poles of memorable? Curiosity and Armstrong no contest.
brighter constellations such as Ursa Major and Cassiopeia, as well as the Summer Triangle asterism. Luckily, while we were on the way to visit our engagement spot near the Eiffel Tower, we were able to observe the International Space Station as it passed overhead. I was able to capture a few frames as the craft tracked across the Parisian sky. Amazingly, by the time we had taken a gentle, romantic stroll back to our apartment less than 2km away, the ISS was already about to pass over the Arc de Triomphe. We spoke to a German couple who were taking holiday snaps of the monument and they were genuinely excited when we informed them that they would soon see the ISS. Even in a heavily light polluted city such as Paris, it is still always worth looking up! Andrew Richens, Long Sutton, Lincolnshire
Thanks for the photo, Andrew, and for taking the time to share your knowledge of the sky with others. – Ed
Contrail correspondence The frustrating threads are woefully common near airports
@astrosphinx The successful landing of the @MarsCuriosity rover, an amazing feat. @Scopeguy I will remember the Venus transit viewed on Mauna Kea for the rest of my life. An incredible event shared with great company. @Vortexical Catching the Perseids for the first time. I counted 14 meteors in an hour through shifting patches of cloud. Awe-inspiring. @BHM2345 Buying my first telescope and seeing Jupiter and the Andromeda Galaxy :) @ojooto First Light with my new ZenithStar 80. And first light for me. Finally found M81 and M82 after a long, slow search, will get better.
Lights drown out most of the stars above Paris, but the ISS can still be seen
contrails and checking the transparency of the atmosphere in both visible and infrared light using photodiodes. Air flights over Cornwall reach a peak on Christmas Eve then drop sharply until New Year’s Day, when they rise again. The atmospheric transparency mirrors this, although with lots of natural cloud. It’s a work in progress to get a comprehensive data set. Clearly this problem has an effect on the night sky too and we plan to adapt the kit to measure the brightness of stars against a number of parameters. Brian Sheen, Par, Cornwall Contrails rarely appear this beautiful
My private cloud cover
The photo above was taken in May 2005 from where I live, 6km from Manchester International Airport. Little has changed today: there are still many contrails over my location. They are, however, not from local flights but from planes flying over the area. I have often said that I have my own private cloud cover due to the presence of a busy airport close by, notably on humid days when the heat generated by various sources at the airport sends damp air skywards to condense (especially at night) in the colder air above. The skyglow from the airport, which is west-northwest from me, already makes any astronomy in this direction very difficult, even on clear nights, without the added problems of contrails and rising damp air. Eric Turner, Wilmslow, Cheshire
Disruption diary
The effect contrails have on cloud cover was observed after 9/11 when all aircraft over the US were grounded: the sky went blue. Between Christmas and New Year, Roseland Observatory in Cornwall will be monitoring
White waterfall
I thought this was a most unusual but very attractive contrail photo. They were spreading and travelling eastwards at a very rapid rate, presumably urged on by the jet stream. Normally, I curse them: we get an awful lot here between Wisbech and the Wash, as there’s a north-south flightpath to the west and an east-west flightpath to the north. If the conditions are right for contrails to form and persist, then with strong winds to spread them, I stand in my dome and huff and puff, but can only retire indoors and restore my humour with a stiff G&T. Stuart Smith, Wisbech
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22 LETTERS DECEMBER
ASTRO CROSSWORD Number 32. Set by PERSEUS
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ACROSS 1 This astrophysicist and priest came up with a theory often credited to someone else (surname). (8) 4 Some stars like to gather in groups; this type of star cluster is more compact and spherical. (8) 6 An ______ 5 carried the Planck and Herschel missions into orbit. (6) 9 _______ has been detected on several comets. (7) 10 The _____ ______. During the early 20th century Shapley and Curtis met for a chat. (5,6) 12 To turn a telescope across the sky. (4) 15 The Big Bang ______ – US sitcom about a group of scientists, starring Jim Parsons. (6) 19 The formation of this nebula may have been witnessed by Chinese astronomers in 1054. (4) 20 Comets tend to have very __________ orbits. (10) 21 Organisation responsible for the Very Large Telescope in Chile. (3) 22 Over the course of a month the Moon appears to ‘nod’. (9) DOWN 1 Vega is part of this grouping of stars. (4) 2 Did this nebula come first? (3) 3 US astronomer who worked at the Palomar Observatory and found jets of material coming from M82’s heart (surname). (7) 5 Mission that studied the Universe at sub-mm wavelengths while dangling under a big balloon (acronym). (5) 7 Shining brightly in Orion. (5) 8 A measure of disorder. (7)
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11 Alnitak, Alnilam and Mintaka all make up Orion’s ____. (4) 12 The stars move across the sky at the ________ rate. (8) 13 ___ Carinae is a star that may soon go supernova. (3) 14 Steady State theory pioneer (surname). (5) 16 Venerable space telescope. (6) 17 This observatory houses a 40-inch refractor. (6) 18 _____-Cygnid meteors may be seen streaking across the sky in August. (5)
The solution to this crossword will be published in the January 2013 issue. Astro Crossword number 31 solution
MARKETING Head of Circulation Rob Brock Head of Marketing Marie Davies Marketing Executive Rebecca Bull Head of Press and PR Carolyn Wray 0117 314 8812 PUBLISHING Publisher Andrew Davies Managing Director Andy Marshall MANAGEMENT Chairman Stephen Alexander Deputy Chairman Peter Phippen CEO Tom Bureau BBC WORLDWIDE MAGAZINES UNIT Managing Director Nicholas Brett Publishing Director James Hewes Editorial Director Jenny Potter Unit Co-ordinator Eva Abramik EDITORIAL ADVISORY BOARD Nicholas Brett, Tom Bureau, Deborah Cohen, Jane Fletcher, James Hewes, John Lynch, Jenny Potter, Kathy Sykes
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ADVERTISEMENT FEATURE
Binocular Vision
Neil Phillipson of Astronomia shows us why two eyes can be better than one if you’re observing the heavens
T
here’s a lot of people out there that will tell you a pair of binoculars can be ‘as good as a telescope’ or at least a great starting point for astronomy. Of course this is an over-simplification, but there is a kernel of truth – there are a great many astronomical objects that look fantastic when viewed with two eyes rather than one. This month I’ll tell you about various types of binocular and what you can expect to see.
Why Binoculars
Binoviewers: Best of both worlds?
With astronomy, the key challenge for our brain is how to interpret very faint data to see more than just grey blobs - and for most of us, we’re pretty used to having two eyes on things. They work together to help the brain see depth and detail, which is why everything feels clearer and more three-dimensional with both eyes!
Magnification Binoculars also have a distinct feature which sets them apart Top Quality from telescopes 10x50: Opticron - they have relatively low SR.GA - £249 magnification. This means that for a given aperture size, they are nice and bright and can bring out the details of objects like star clusters where a telescope might fail. Of course there’s a down-side to this too – most binoculars are pretty useless when it comes to planetary observing, because they just don’t have the power. Binoculars usually have two numbers in a recognisable format printed somewhere on them, e.g. 10x50. The first number is the magnification (in this case 10) and the second is the diameter of the front objective lenses – the aperture. For wide-field observation, a low magnification is best – say 6x to 10x. Put a 7x50 binocular to your eyes and you will see many times more stars than you could with the naked eye – that’s the fantastic brightening effect of the optics. Higher magnifications of 15x to 25x will start to bring out some of the larger galaxies and nebulae – but beware – a 7x binocular is about the limit for hand-holding, so you’ll need a tripod!
Aperture The larger the objective lenses of the binocular, the more light they gather and this of course improves the brightness of the view. At higher magnifications, you’ll need the brightness in order to bring out some of the fainter objects. The drawback is that large-aperture models tend to have larger magnifications, which effectively stretches out
Great Value: Celestron SkyMaster 20x80 – £125
Pleiades: Image byJohn Slinn
the gathered light and reduces the brightness. It’s a balance that can be hard to get right!
The Package There are a couple of other aspects of the package you should consider too... can you focus both eyes together (centre focus) or do you have to focus each eye separately? How do they mount to the tripod, and is it stable? Do you need a taller tripod to comfortably observe near the zenith? Consider the style of the eyecups too. Twist-up types allow comfort with or without glasses, whereas cheaper models will sometimes come with a less comfortable flexible rubber eyecup. Our best advice is always to try out a range of binoculars before buying: these are personal things and no two people’s faces, eyes and eyelashes are the same shape. Make sure you will be comfortable using them for a period of time before splashing out. Head for a dealer that has a good range and space to try them properly. No Something Special: prizes for guessing Helios Quantum 7.4 - £1,699 who I’d recommend!
If you already own a telescope, there is a way for you to harness the power of both eyes – and it’s called a binoviewer. The binoviewer essentially splits the image in two delivering half the light to each of two eyepieces. This allows a very similar view to a binocular but harnesses all of the magnification of the telescope, making it possible to view the Moon and planets with both eyes. However, to do this, the binoviewer must extend the ‘back-focus’ of the telescope (the distance from the back of the telescope at which the image is formed). This is done by a nosepiece lens with a typical 2x magnification, so the view through a binoviewer will be more magnified than with a single eyepiece. Of course the light gathered also has to be shared between two eyepieces, though many accept that this is compensated for by the advantages of using two eyes. Binoviewers start from around £150.
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Hotshots This month’s pick of your very best astrophotos PHOTO OF THE
MONTH
p Messier 39 WILLIAM McSORLEY LEEDS, 29 JULY 2012 William says: “I was absolutely blown away with the number of background stars I had captured and how clean the image was, particularly given the light pollution from nearby Leeds. So much so that the data needed very little post-processing.”
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Equipment: QHY8L cooled CCD camera, Sky-Watcher Explorer 150P reflector, EQ5 Go-To mount Sky at Night Magazine says: “William has captured the subtle star colours in and around M39 beautifully. The mass of stars in the background really sets off the bright, sparkling cluster itself.”
About William: “I have always been interested in ‘what’s up there’, but it wasn’t until the very first Stargazing LIVE series that I thought ‘I want to get into astrophotography’. Since then I have worked hard on the steep learning curve, imaging as often as weather permits here in the UK.”
HOTSHOTS DECEMBER 27
Noctilucent clouds
The Milky Way
GORDON MACKIE DUNNET HEAD, CAITHNESS, 11 AUGUST 2012
LUIS ARGERICH SAN ANTONIO BAY, ARGENTINA 24 JULY 2012
Gordon says: “Myself and a few other members of Caithness Astronomy Group gathered at this dark location to enjoy the Perseid meteor shower. We were treated to a delightful bonus – a late-season display of noctilucent clouds that shone brightly as darkness fell.” Equipment: Olympus E-420 DSLR camera
Luis says: “This photo shows the Milky Way and the Magellanic Clouds. I took it from the bottom of the San Antonio Bay when the tide was low; a few hours later the place was totally underwater.” Equipment: Canon EOS 5D MkII DSLR camera, 14mm lens
The Triangulum Galaxy TERRY HANCOCK MICHIGAN, US, 7 OCTOBER 2011 Terry says: “It was my goal to go as deep as possible in order to capture the very faint outer spiral arms, the dusty regions and the colourful HII nebulae while trying to retain a natural appearance.” Equipment: QHY9M monochrome CCD camera, TMB-130SS refractor, Paramount GT-1100S with MKS4000 mount
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Solar mosaic GARY PALMER SUTTON, SURREY 10 AUGUST 2012 Gary says: “This is a 76-panel mosaic of the Sun. It was imaged through a bit of high cloud. Each panel is made up of 600 frames.” Equipment: Imaging Source DMK 31 CCD camera, SolarMax II 3.5-inch solar telescope, Celestron CGEM mount
The Dumbbell Nebula TOM HOWARD CRAWLEY, SUSSEX 23 JULY 2012 Tom says: “Following weeks of cloud and rain, I took advantage of a short break in the weather to capture this image of one of the biggest and brightest planetary nebulae in the sky.” Equipment: Nikon D7000 DSLR camera, Meade 5000 ED apo 5-inch refractor, EQ6 mount
The Moon STEVE WARD RED LODGE, SUFFOLK 1 AUGUST 2012 Steve says: “I’m always amazed by the brightness of the full Moon on a clear night. It’s easily light enough to read by.” Equipment: Canon EOS 1000D DSLR camera, Sky-Watcher ED80 Pro refractor, 1.8x Barlow lens, EQ3-2 mount
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ESO
If you’re looking for an extra challenge, seek out the beautiful Cone Nebula in Monoceros; you’ll need a 10-inch scope to spot it
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WINTER WONDERS DECEMBER 33
Winter
ABOUT THE WRITER Steve Richards is an expert deep-sky imager. He compiles the monthly Deep-sky tour on page 56 of each issue.
wonders Our experts join Steve Richards on a seasonal tour around 10 celestial sights you won’t want to miss this Christmas
T
he countdown to Christmas is always exciting, but for astronomers it’s doubly so as it’s a great time to head out observing. The nights are long, and often crisp and clear, though you shouldn’t underestimate just how cold it can get.
In this article, we’re going to point out 10 stunning night-sky highlights you can see this festive season – and the Sky at Night Magazine and TV show teams weigh in with why they find them so outstanding. There is a range of objects and events for you to savour: for some we
have charts to help you to find them. So wrap up warm and enjoy! Many of these objects will be on display all month, but remember that there’s going to be a new Moon on 13 December – bear these darker skies in mind when planning your stargazing. >
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10
The Orion Nebula
WILL GATER X 3, CHART: PETE LAWRENCE
Our first object, the Orion Nebula, is a ‘must see’ delight. For many it provides a first taste of the deep sky. It’s visible to the naked eye and simple to find in the constellation of Orion. The shape of the constellation itself is hard to miss thanks to the prominence of the three stars that make up Orion’s Belt: Alnitak, Alnilam and Mintaka, which range in brightness from mag. +1.7 to mag. +2.4. The belt is the starting point for locating the nebula. Hanging from its centre is Orion’s sword; within the sword, flanked north and south by bright stars, is a bright misty region that is clearly not stellar – this is the Orion Nebula, M42. The bright core is home to the Trapezium, a trapezoid shape of four bright young stars. The nebula itself fans out into a glorious region of sculpted gas and dust – there’s plenty to see here if you’re using binoculars or a telescope.
Even through a small telescope, the complex structure of the gas curling this way and that creates an impression of threedimensional structure that’s really special – this is a truly glorious object! Chris Lintott, The Sky at Night
The Orion Nebula is a relatively easy spot, but not one that is easily forgotten
NGC 869 appears above NGC 884 in this shot; you may be able to glimpse the pair with your eyes alone under dark skies
9
The Double Cluster Our next stop also has a sword connection – it’s the Double Cluster in Perseus, which is sometimes known as the Sword Handle. Imagine a line from mag. +2.2 Gamma (γ) Cassiopeiae to mag. +2.7 Ruchbah (Delta (δ) Cassiopeiae) and continue along it for about twice the distance again to find this delightful object. It’s a two for one view, comprising open clusters NGC 884 and NGC 869. The pair are a delight through binoculars, though like the Orion Nebula you should be able to see them with the naked eye, especially from a dark location. Both star clusters contain numerous hot, young supergiants, white-blue in colour, as well as a sprinkling of prominent red giants. At 7,600 and 6,800 lightyears from us respectively, they are also relatively close to one another. Neither cluster features in the Messier catalogue, but they are included collectively in Patrick Moore’s, as Caldwell 14. The Double Cluster is a wonderful object to observe and image. I particularly love the differences in star colour that can be found within NGC 884. Will Gater, features editor
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WINTER WONDERS DECEMBER 35
8
M66 nestles above M65 on the left of the Leo Triplet, with the abrupt edge-on streak of NGC 3628 completing the triangle
The Leo Triplet From a doublet to a triplet, we move to a grouping of three spiral galaxies in the constellation of Leo, the Lion. A couple of hops are required to reach the trio. Start from the Lion’s ‘hip’, mag. +3.3 Chort (Theta (θ) Leonis). Move south 2º to mag. +5.3 star 73 Leonis, then east 1º to find the galaxies. The brightest of the three is oval-shaped M66. M65, the second brightest, is more cigar-shaped and has a less-distinct core than M66, but both are visible in large binoculars or a small telescope. NGC 3628 completes the line up, though its edge-on orientation can make it quite elusive. You’ll need a 6- to 8-inch telescope. Placing M65 and M66 along the southern edge of the eyepiece will allow you to see all three at about 65x magnification. The Leo Triplet holds the wonder of seeing three distant but bright galaxies. M65 and M66 are the closest together, with fainter NGC 3628 hanging above them. Paul Money, reviews editor
7
4 Vesta and Ceres 4 Vesta and Ceres both reach opposition this month, which makes finding them that little bit easier. Asteroid 4 Vesta is just 530km-wide, but will be mag. +6.4 at opposition on 9 December, making it an easy sight in binoculars. It’ll be about 7.5° east of orange mag. +0.9 star Aldebaran (Alpha (α) Tauri) – refer to the chart, right. Dwarf planet Ceres is a bit bigger, with a diameter of 932.6km. It’s at opposition on the 17th, when it be mag. +6.7. If you want to see it on the 9th as well, it will be visible in binoculars roughly 5º southeast of mag. +1.7 Elnath (Beta (β) Tauri). Some people claim that at opposition Ceres does not ‘twinkle’ like a star and looks non-stellar in binoculars, unlike 4 Vesta. Try looking for them and see what you think! Paul Abel, The Sky at Night
Look south at around midnight, at an altitude of 50º, to see 4 Vesta and Ceres in December
ι
M38
AURIGA
M36
M37
Elnath
TAURUS
β
Jupiter
NGC 1746
ε
Ceres
13 Dec 9 Dec 5 Dec
χ2
χ1
NGC 1647
V
γ
Aldebaran
M1
ζ
δ1
Vesta 5 Dec
NGC 1817
13 Dec
α
9 Dec
NGC 1807
ORION
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36
You may feel these stars look familiar; many people see an echo between the stars in the Pleiades and the ‘bowl’ of the Plough
6
The Pleiades Our next object is arguably one of the most beautiful open clusters in the night sky – the glorious Pleiades in Taurus. At just under 2° across, this cluster is clearly visible to the naked eye in most conditions, so it’s very simple to find. Start from Aldebaran and sweep northwest;
you should be able to identify at least six of the cluster’s 500 or so member stars with the naked eye. The four most prominent stars form a trapezoid reminiscent of the ‘bowl’ of the Plough. One of the brightest stars, Merope, has a lovely bent line of stars extending to the east that is visible at low magnification in binoculars or a wide-field telescope – indeed, low magnification is generally the best way to enjoy the majesty of this
CHART: PETE LAWRENCE, BABAK TAFRESHI/TWAN/SCIENCE PHOTO LIBRARY
5
cluster. A passing cloud of dust gives a gentle bluish hue to the bright young stars through their reflected light. Perhaps the most beautiful deep-space, naked-eye object; it’s a perennial challenge to count the constituent bright, young stars of this jewelbox cluster. Mark Parrish, astronomy writer
This brilliant alignment occurs on the 5th at 6.30am; planet sizes have been exaggerated for clarity
Mercury, Venus and Saturn before dawn Mercury never strays too far from the Sun, but it will be a healthy 20° west of our star before dawn on 5 December. The planet will be 7° to the east of an 89 per cent illuminated Venus, which will itself be just 1.8º northeast of mag. +2.8 Zubenelgenubi (Alpha (α) Librae). But the main event that morning is the alignment of Mercury, Venus and Saturn in the pre-dawn sky. Saturn’s rings will even be at their most exposed angle for the whole year during December. Alignments like this put the ecliptic plainly on view and are a great reminder of our place in the Solar System. A nice opportunity for naked-eye viewing and close-up work on Saturn. Chris Bramley, editor
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Spica
Saturn
Venus
Mercury
SOUTHEAST
WINTER WONDERS DECEMBER 37
4
The winter constellations The winter constellations are not to be missed. Mighty Orion dominates the night sky with his broad shoulders and prominent belt stars. And although the Orion Nebula is the constellation’s showpiece object, there is plenty more to see and photograph within it. Similarly, Taurus has much to offer with numerous open clusters visible within its boundaries, including the famous Pleiades and Hyades. Gemini, with its bright main stars Castor and Pollux, paddles within the misty band of the Milky Way and is home to many open clusters and nebulae. You should not neglect the constellations of Canis Major and Canis Minor either. Within their boundaries lie several fine double stars, a glittering open cluster (M41) and Sirius (Alpha (α) Canis Majoris), the brightest star in the sky. The constellation of Cancer is often overlooked at this time of year too. This month be sure to enjoy the Beehive Cluster and fellow open cluster M67 – the latter is one of the oldest open clusters that we know of. The stars of winter are more brilliant than any others and dark skies make observing them particularly fascinating. Look up into a clear sky on any winter’s evening and you will find a great deal to interest you. Patrick Moore, The Sky at Night
Grand Orion is among the most recognisable constellations thanks to his glittering bright stars
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3
PETE LAWRENCE, SCIENCE PHOTO LIBRARY, THINKSTOCK
The opposition of Jupiter
Jupiter, taken during its October 2011 opposition. The planet won’t appear as large in 2012, but it will climb higher in the sky
Jupiter will be a particularly fine sight this month, as the planet reaches opposition on 3 December. Look for it around midnight, when it will be 5° due north of Aldebaran in Taurus, at an altitude of about 60°. The planet has a fascinating series of cloud belts. The two most prominent, the North and South Equatorial Belts, are easily visible in a small telescope. Jupiter’s family of 60 or more moons is as fascinating as the planet itself. The four we call the Galilean moons – Ganymede, Io, Europa and Callisto, so named because they were discovered by Galileo Galilei in 1610 – are visible in binoculars, appearing as little pinpricks of light. Jupiter is the largest of our Solar System’s planets but not the brightest; that title is held by Venus. Nonetheless it always outshines mag. –1.4 Sirius, the brightest star in the sky. Oppositions of Jupiter are an opportunity for us to study its cloud tops in fine detail. Even with modest equipment you can’t fail to be impressed with the largest planet in our Solar System at this time. Steve Marsh, art editor
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The Geminid meteor shower Meteor showers can both surprise and disappoint, but they remain a great excuse for getting your sunbed out in the middle of winter! Wrapped up against the elements and lying back comfortably is a great way to watch these celestial fireworks, and the Geminids promise to put on a great show this year. The peak of activity will take place on the night of 13 December. With a new Moon on this night, only the clouds have to play fair to make this a very special occasion. The radiant, near Castor in Gemini, will be at its greatest elevation at about 2am – you just need to make sure you’re comfortable and ready to enjoy the show. Check out our detailed guide to the Geminid meteor shower on page 50 for more information.
The Geminids are one of the most active of all the meteor showers – an event not to be missed if you’ve never seen a ‘shooting star’
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For me, the Geminid meteor shower is the best of the year. With more than 100 meteors per hour due on the night of the peak this has the potential to be an exceptional event. Pete Lawrence, The Sky at Night
WINTER WONDERS DECEMBER 39
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The Sun’s increasing activity makes it more likely that the aurora will be visible from the UK – even in the south
The Northern Lights Auroral displays are rarely seen well from the UK, but with the Sun approaching solar maximum, the point in its 11-year cycle of activity when a peak is predicted, there is a heightened expectation that there may be some good displays in the next 12 months. This is by no means guaranteed, as the Sun has a reputation of not running to form, but if estimates are correct there is a reasonable chance that aurora will occasionally be seen even at the UK’s relatively southern latitudes. The farther north you are, the better the chance you have of observing this wonderful phenomenon, so why not consider a trip to Norway, Iceland, Finland or Sweden, where you’ll be much closer to the Arctic? Several companies also operate aurora flights that fly you to the far north of Scotland to view the Northern Lights from the air. S I love watching the aurora magically morph from a subtle green glow on the horizon into bright beams, flowing curtains or enormous swirling shapes hovering overhead – an absolutely stunning sight. Carol Lakomiak, sketching expert
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Sky at Night MAGAZINE
celebrates the Apollo missions
40 YEARS ON WORDS: MARK BOWYER
7 December 1972
Apollo 17 The last manned Moon mission was still a pioneering endeavour of a great many firsts
A
lthough Apollo 17 was the last mission to put astronauts on the Moon, the programme was brought to a close by decisions made years before its launch on 7 December 1972. When NASA conceived Apollo in 1960, it was against a backdrop of intense political passions. The Cold War was in its ascendancy, and the US and the USSR were locked in the battle of wills we know today as the Space Race. Apollo was mooted months before Soviet cosmonaut Yuri Gagarin completed his historic journey beyond Earth’s orbit, yet calls for funding fell on deaf ears. But it was this Soviet success that galvanised the White House – within two months US President John F Kennedy pledged that the country would land a man on the Moon and bring him back before the decade was out. And so Apollo, as we know it, was born.
NASA had 15 Saturn V rockets to use in Moon landing attempts. Apollo 11, the mission that delivered on Kennedy’s promise, used the sixth of these, leaving nine more for Apollo missions 12 through 20. But with Neil Armstrong’s first steps all but securing victory in the Space Race, NASA was soon under pressure to reduce its spending – the entire programme had required a funding commitment of some $25 million. Apollo 20 was the first victim, cancelled in January 1970. Apollo 18 and 19 were culled in September of the same year, and NASA subsequently re-planned the remaining flights. Apollo 17, originally destined for the Marius Hills in the Oceanus Procellarum, was now bound for Taurus-Littrow, a lunar valley on the edge of the Mare Serenitatis. The landing site had shown promising signs of recent volcanic activity when Apollo 15 imaged it the year before.
MEET THE CREW EUGENE ANDREW CERNAN MISSION COMMANDER
RONALD ELLWIN EVANS COMMAND MODULE PILOT
HARRISON ‘JACK’ SCHMITT LUNAR MODULE PILOT
Born on 14 March 1934 in Chicago, Cernan studied aeronautical engineering while at the Naval Postgraduate School and joined NASA in October 1963. He flew as pilot on Gemini 9 and travelled to the Moon on Apollo 10, the ‘dry run’ for Apollo 11, coming within 15,250m (50,000ft) of the lunar surface during the landing rehearsal. Cernan left NASA in 1976 to work in private business.
Born on 10 November 1933 in St Francis, Kansas, Evans also studied aeronautical engineering at the Naval Postgraduate School. He joined NASA in 1966. Apollo 17 was his only space flight, although he also served as the backup command module pilot on Apollo 14. He left NASA in 1977 to work in industry. Evans died of a heart attack on 7 April 1990, aged 56.
Born on 3 July 1935 in Santa Rita, New Mexico, Schmitt was the first scientist astronaut to fly on a NASA mission. He joined the space agency in 1965. Before becoming a pilot, he had helped to design the geological training for the early Apollo missions with the US Geological Survey. Schmitt entered politics after he left NASA in 1975, becoming the Republican senator for New Mexico from 1977 to 1983.
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APOLLO 17 DECEMBER 41
Apollo 17 was the first manned night launch from the Kennedy Space Center
Cernan takes the rover for a test drive on the lunar surface
Þ Taurus-Littrow as seen from the lunar module; the command module is visible near the centre of this image
to reducing the loss of scientific data returned due to the cancellation of the final three missions. Two minor technical issues delayed the launch of the Saturn V carrying mission commander Eugene Cernan, command module pilot Ron Evans and Schmitt for two hours and 20 minutes. Lift off was at 12.33am. Following a perfect ascent and check out, the third stage fired again to increase the highest point of their orbit to match the distance to the Moon. The command service module America and lunar module Challenger undocked from their spent rocket and coasted on.
Tight landing Apollo 17 entered lunar orbit some 83 hours after launch. The launch delay had been countered by a faster than expected trip to the Moon – a good thing, as the angle of the Sun would help Cernan and Schmitt watch for obstacles as they landed. The landing was tricky: the typical touch down ellipses for Moon landings had been 3km by 2km, but to safely land in Taurus-Littrow, that had to be reduced to a 1km circle. Cernan brought Challenger down on a flat spot well within the target area. Schmitt, who on the coast to the Moon had kept up a steady commentary on the cloud formations he saw back on Earth, was finally silenced as they got their first close look at the surface. Recovering quickly, he exclaimed, “Oh, man! Look at that rock out there!” In common with the previous crews, both Schmitt and Cernan had trouble estimating distances and sizes without any familiar cues or haze towards the horizon. Only four hours after landing Cernan was ready to step off the ladder. He dedicated his first step on the Moon to “all those who made it possible”. > skyatnightmagazine.com 2012
ALL PHOTOS: NASA
But although Apollo 17 was the final mission, it was still a mission of firsts. It was the first manned night launch from the Kennedy Space Center, though that didn’t stop an estimated half a million people gathering to watch, including, for the first time, Patrick Moore. Another first was the inclusion of a trained scientist on the crew roster – lunar module pilot Harrison Schmitt – and this went a long way
42 APOLLO 17 DECEMBER
Schmitt during the second rover outing at Crater Shorty, which dips off the right of the image
MISSION TIMELINE 7 DECEMBER 1972 05:33 GMT (00:33 LOCAL TIME) The final mission in the Apollo programme lifts off.
3 HOURS, 12 MINUTES Check out in Earth orbit is completed. The command service module’s engine fires for 351 seconds, sending the mission Moonwards.
86 HOURS, 14 MINUTES The command service module’s engine fires for 393 seconds to reduce speed, allowing the craft to be captured by the Moon’s gravity.
113 HOURS, 2 MINUTES
>
The crew lands on the lunar surface on target with over two minutes of propellant remaining.
117 HOURS, 11 MINUTES Cernan steps off the ladder onto the lunar surface.
170 HOURS, 41 MINUTES Final entry into the lunar module. Cernan becomes the last man to walk on the Moon.
Schmitt found orange soil at Shorty, sparking theories that the Moon had see recent volcanic activity
185 HOURS, 21 MINUTES Lift off from the Moon. The launch is captured by the lunar rover’s camera.
191 HOURS, 18 MINUTES The ascent stage of the lunar module is jettisoned and its engine is fired to crash it into the Moon. This provides data for the seismometers left at the Apollo landing sites.
255 HOURS Evans leaves the command module to retrieve film from the service module.
NASA X 3
301 HOURS, 51 MINUTES Splash down in the Pacific Ocean.
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Cernan and Schmitt, the last men to walk on the Moon, photographed by Evans on the return journey to Earth
> Schmitt quickly joined him on the surface and
almost at once started a running commentary on the types of rock he could see close by. With the most distant objective for the first Moon walk only 2km away, the pair started their work close to the lunar module. The lunar rover that would allow them to traverse the entire width of the valley proved easy to deploy and setting up the scientific station also went smoothly. Only 30 minutes behind schedule, Schmitt and Cernan had completed the first set of tasks and were ready to explore farther afield. The high work rate set in the first Moon walk was repeated on a further two journeys out in the rover. During the second outing, at Crater Shorty, Schmitt caused a stir among the scientists on Earth when he found an orange deposit. Was this evidence of recent lunar activity? When analysed, the data showed that the area had been volcanically active, but it was far from recent – studies have shown that it occured 3.72 billion years ago. In total, Cernan and Schmitt covered 35.75km and returned 63kg of samples. As Cernan paused, taking a last look before climbing into the lunar module for the final time he said, “As we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return, with peace and hope for all mankind.” And with that, our presence on the Moon came to an end – for now. S
ADVERTISEMENT FEATURE
International Astronomy Show
May 2013 Here’s a great gift idea for anyone interested in the stars - tickets for the very first International Astronomy Show. This exciting new show, which aims to be the biggest outside London, brings together over 40 astronomy dealers and specialists in a 2000 square metre exhibition space. There will be a series of fascinating talks by some of the country’s best known speakers and some lively demonstrations to add to the fun. The show will be held in May 2013 at the Warwickshire Exhibition Centre. This venue has easy access by road and rail, a shuttle bus from the station and free parking for 2000 cars. With an excellent 200 seat restaurant and all ground floor exhibition space this new show is sure to be a stress free, stimulating and enjoyable event. Go to the website for more details and ticket sales international-astronomy-show.com
Vixen Polarie
Price £399 Take amazing photos of the night sky with the Vixen Polarie – just place this compact and portable device between your D-SLR camera and tripod and you can shoot long-exposure images of the sky with pin-sharp stars. It also includes modes for lunar and solar photography. For more details visit astronomia.co.uk
ASTRONOMERS’
Gift Guide
Energizer Pro 7-LED Headlight
Price £19.99 Don’t fumble in the dark – illuminate your kit with this excellent quality LED headlight from Astronomia. With three white-light modes for outdoor activity, plus a red mode that preserves your nightvision, it’s a versatile tool for astronomers, walkers and more. For more details visit astronomia.co.uk
APM 2.7x Coma Correcting APO Barlow
Price £125 When combined with the Pierro Astro ADC this APM APO Barlow will allow you to experience the planets like never before! For more details please visit apm-telescopes.co.uk
Pierro Astro ADC
Price £329 This high quality Atmospheric Dispersion Corrector will improve your view of the planets forever! Add the APM Barlow for the ultimate view! For more details please visit pierro-astro.co.uk
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THE CHRISTMAS
SURVIVAL GUIDE IN CASE
OF CLOUDS SEE BELOW
It’s late afternoon on Christmas Day: the dirty dishes are languishing in the sink, the detritus from the day’s festivities lies scattered all around, and the faint whiff of Christmas crackers and turkey fat lingers in the air. What’s more, the forecast for the next week is nothing but cloud and drizzle, and you just can’t face another repeat of Mary Poppins on TV. What’s an astronomer to do in such testing times? Well, we reckon we’ve got the answer. We’ve compiled the ultimate Christmas survival guide for stargazers. From apps to websites, gadgets to our legendary (alright, not quite) quiz, there’s something to keep you occupied during all that downtime. Merry Christmas!
ASTRO QUIZ OF THE YEAR APPS TO AMUSE F-Sim Space Shuttle
Take control of the Space Shuttle during its landing phase and bring it safely down to Earth. Mission control audio playing in the background adds a nice touch of realism and the graphics are impressive. Daring pilots can customise the weather, landing site, wind speed and more. iPad/iPhone; download from iTunes; £2.49
Spacecraft 3D
Have you been paying attention? How will you rate? 0-3: space junk. 4-7: brown dwarf. 8-11: main sequence. 12-15: supernova! Turn to page 88 for the answers. 1 The Space Shuttle Discovery took up residence in which museum in April of this year? 2 What’s the name of the Martian crater that the Mars Science Laboratory landed in this August? 3 What did billionaire Jeff Bezos say he wanted to salvage in March of this year? 4 The Moon occulted which open cluster in late May?
THINKSTOCK X 2, NASA/JPL-CALTECH
5 Complete this headline from one of the news articles in July’s issue: “Did white dwarfs munch on ______ ________?” 6 A total solar eclipse was visible across which two Australian states in November? 7 The winning image of the 2012 Astronomy Photographer of the Year competition was a picture of what? 8 In March we celebrated the 40th anniversary of the launch of which planetary space probe?
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9 May saw the arrival of the first commercial resupply craft at the International Space Station. What was its name? 10 What was the 55th object in the ‘Moore Marathon’, which we featured in our April issue? 11 Which famous physicist celebrated his 70th birthday this year? 12 Which Somerset town temporarily switched off its streetlights for this year’s Stargazing LIVE series? 13 NASA’s Dawn mission left the asteroid 4 Vesta in September; which Solar System object is it heading to now? 14 The first man on the Moon, Neil Armstrong, died in August; what was the first Gemini mission he flew on? 15 And finally… complete this news headline from our October issue: “Sun more _____ than expected.”
Christmas isn’t just about toys for the kids – this augmented reality app from NASA lets you play with the Curiosity rover. Print out the reference ‘marker’ and look at it with the camera on your iPhone or iPad. The app creates a 3D model of the rover on screen in place of the marker. iPad/iPhone; download from iTunes; £free
Moon Atlas
Of all the apps we have this is the one that we use the most. This brilliant guide to the lunar surface is great if you want to learn the names and locations of the lunar seas and major craters. It includes moonrise and moonset times, and a libration graph to help you plan your observing. iPad/iPhone; download from iTunes; £3.99
Apollo 11: The Game,
Fly the Apollo 11 mission from the training stages in the ‘flying bedstead’ to the return to Earth. You’ll have to make course corrections as you fly towards the Moon and get the lunar module down to Tranquillity Base in one piece. Each stage is introduced with a short piece of actual Apollo footage too. iPad/iPhone; download from iTunes; £1.49
CHRISTMAS SURVIVAL GUIDE DECEMBER 45
COSMIC KIT
Personal planetarium
If Christmas brings clouds, this miniature planetarium will keep you entertained. It projects thousands of stars onto the ceiling of a darkened room and there’s a meteor function too. Before long you’ll have forgotten what ‘occluded front’ even means. www.iwantoneofthose.com; £69.99
Astronaut ice cream
Assuming the mountain of turkey, spuds, Brussels sprouts and gravy doesn’t defeat you, why not finish up Christmas lunch with some ‘traditional’ astronaut ice cream. It doesn’t taste that bad, but its consistency is akin to florist’s foam. www.firebox.com; £5.99
ON THE WEBSITE
Looking for a perfect project for a rainy Christmas afternoon? You’ll find a selection of How to articles from our archive on our website at http://www. skyatnightmagazine.com/astronomy-for-beginners/howto
Build a Bahtinov mask
Getting sharp astro images requires perfect focus. This clever accessory, known as a Bahtinov mask, can make this much easier. Our article shows you how to make one – just remember to take it off the front of the scope before imaging!
What better way to mark the end of the Shuttle era than building a 1:72 scale model of the iconic craft? The 111-piece kit from Revell includes decals for Atlantis, Discovery and Endeavour, and the finished model measures 48.9cm long and 36cm wide. www.modelzone.co.uk; £39.99
WEB WONDERS EYES ON THE SOLAR SYSTEM
This brilliant browser-based program allows you to fly through the Solar System alongside many of NASA’s most famous spacecraft. It’s easy to lose hours exploring what the inner Solar System looks like from the distant New Horizons probe or following the Cassini spacecraft as it zooms around Saturn. http://eyes.nasa.gov
Keep your scope’s optics clean
These two comprehensive guides will shows you how to keep the lenses and mirrors of your beloved scope in tip-top condition, ready for when the skies clear (yes we laughed when we wrote that too...)
Space Shuttle 1:72 scale model
STAR IN A BOX
This online interactive simulator allows you to see how stars of different masses evolve. Thankfully, you don’t have to wait millions of years for that to happen, as all the action is considerably sped up. You can also change the mass of the star in question and see what effect that has over time. www.lcogt.net/siab
PAPER MODEL OF JWST
Collimate your Newtonian telescope
If you’ve had one to many mulled wines you might want to sit this one out: collimating a Newtonian telescope requires small, careful movements and attention to detail. This guide explains how to do it.
The James Webb Space Telescope is set for a launch sometime in 2018. Scientists have been working on Hubble’s highly advanced heir for many years; hopefully it shouldn’t take quite that long to make this cool paper model. All the templates and instructions are on the NASA JWST website. www.jwst.nasa.gov/papermodel_swales.html
GALAXY ZOO 4
Citizen science project Galaxy Zoo lets you do real research from your favourite armchair. Go online, check out the galaxy images and classify them according to their shape – you’ll be helping astronomers work out how these vast structures form. A new set of images has been added just in time for Christmas. www.galaxyzoo.org
skyatnightmagazine.com 2012
46 CHRISTMAS SURVIVAL GUIDE DECEMBER
PICTURE PUZZLE
Turn to page 88 for the answers.
2. What’s the name of the rover in this image?
3. Who is this famous astronomer?
1. What’s the name of this moon, and which planet does it orbit?
THINKSTOCK X 2, NASA/JPL/SPACE SCIENCE INSTITUTE, WILLIAM D. BACHMAN/SCIENCE PHOTO LIBRARY, SIMON FRASER/SCIENCE PHOTO LIBRARY, NASA/ JPL, NASA/ESA/C.R. O’DELL (VANDERBILT UNIVERSITY) AND M. MEIXNER/P. MCCULLOUGH AND G. BACON ( SPACE TELESCOPE SCIENCE INSTITUTE)
4. Where would you find this crater?
6. What are these two telescopes called?
skyatnightmagazine.com 2012
5. In what constellation would you find this object?
THE SKY GUIDE DECEMBER 47
December The Sky Guide
Jupiter at opposition
Magnificent Jupiter reaches opposition on the 3rd, when it will appear at its largest and brightest for the current observing period. This particular opposition is a good one as the planet will reach an altitude of nearly 60º for observers in the UK.
OUR STARGAZING EXPERTS PETE LAWRENCE As well as writing The Sky Guide, Pete can be seen on BBC TV’s The Sky at Night every month. On page 60, he shows you how to use infrared filters to get better shots of Jupiter. PATRICK MOORE The presenter of The Sky at Night writes our Moonwatch column on page 59. A renowned lunar observer, his map helped early Russian probes reach the Moon.
PETE LAWRENCE
CAROL LAKOMIAK Carol lives in Tomahawk, Wisconsin, where she bravely goes out observing even when the local wolf pack can be heard howling! She shares her sketching tips on page 58. 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. skyatnightmagazine.com 2012
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HIGHLIGHTS Your guide to the night sky this month This icon indicates a good photo opportunity
2
SUNDAY Mag. +0.8 Saturn, mag. –3.9 Venus and mag. –0.3 Mercury form a line in the early morning sky before sunrise. Catch the trio of planets from 06:00 UT onwards, low in the southeast. The pattern persists for another week, so don’t fret if the clouds spoil the view today.
3
MONDAY The waning gibbous Moon (75% lit) passes in front of open cluster M67 in Cancer, pictured right. Keep watch from about 22:45 UT onwards. The cluster will vanish behind the Moon’s bright edge, reappearing just after midnight. See page 51.
Jupiter is at opposition.
5
9
SUNDAY There are four good dates to see mag. +2.1 eclipsing binary Algol (Beta (b) Persei) dim this month, and the first is this morning at 05:30 UT. Algol dips from mag. +2.1 to +3.4 during its primary eclipse. The other dates are the 12th at 02:24 UT, the 14th at 23:12 UT and the 17th at 20:00 UT.
WEDNESDAY Jupiter’s Great Red Spot is centrally positioned on the planet tonight at around 23:00 UT. From tomorrow until the 21st will be a good time to take this month’s deep-sky tour – find out more on page 56.
12
WEDNESDAY This morning’s pre-sunrise sky has Venus, Mercury and a very thin crescent Moon (1% lit) in an almost straight line low in the southeast. See page 51. Jupiter’s Great Red Spot is centrally placed on the planet just before midnight.
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THURSDAY This year’s Geminid meteor shower should be a good one. The Moon will be new, so won’t interfere at all. Peak activity is estimated for 23:30 UT with a zenithal hourly rate of 120 meteors per hour. See page 50.
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FRIDAY At precisely 11:12 UT the Sun will reach its lowest position in the sky for 2012 – a point in time known as the winter solstice. After this the Sun will begin to climb higher in the sky and the nights will start getting lighter.
25 PETE LAWRENCE X 7
TUESDAY Look southeast just after 07:00 UT to see mag. –3.8 Venus, mag. –0.5 Mercury and mag. +1.0 star Antares (Alpha (b) Scorpii) form a triangle close to the horizon. Jupiter’s Great Red Spot is centrally placed on the planet at around 19:40 UT.
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FRIDAY Orion’s Sword, which includes the fabulous Orion Nebula, reaches its highest point in the sky around midnight. With the Moon out of the way, this is a great time to explore this fascinating area of the sky.
10
MONDAY The waning crescent Moon (13% lit) lies just over 5º to the southwest of mag. +0.8 planet Saturn just before dawn. You should be able to spot the pair from 05:00 UT onwards. See page 51.
THE SKY GUIDE DECEMBER 49
What the team will be observing in December
4
TUESDAY Mercury reaches greatest western (morning) elongation, being separated from the Sun by 21º.
11 15
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Terms you need to know
18
TUESDAY Dwarf planet Ceres is at opposition in the constellation of Taurus. At mag. +6.7 you’ll need at least a pair of binoculars to spot it.
UNIVERSAL TIME (UT) Throughout this guide we’ve used Universal Time (UT), the standard time used by astronomers worldwide. UT is the same as GMT. RA (RIGHT ASCENSION) AND DEC. (DECLINATION) These co-ordinates 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
SATURDAY
The Ursid meteor shower peaks tonight. It has a zenithal hourly rate of 10 meteors per hour, but can exhibit rate enhancements of 50-plus meteors per hour. The waxing gibbous Moon (76% lit) sets at 03:00 UT, leaving the rest of the night clear for observing.
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Carol Lakomiak “I’ll be spending time with the Orion Nebula – it’s always a lovely sight, whether you’re taking a quick look through binoculars or studying its wispy tendrils through the larger aperture of a telescope.” Will Gater “I’m hoping there will be some of the white stuff around so I can shoot snowy winter nightscapes from my favourite dark sky site.”
TUESDAY There’s a great opportunity to spot little Mercury in this morning’s pre-sunrise sky. Mag. –3.8 Venus and the waning crescent Moon (6% lit) should be quite easy to spot in the southeast from about 06:30 UT. Mag. –0.5 Mercury lies farther to the east and lower down. See page 51.
SATURDAY Look out for the waxing crescent Moon (7% lit) low in the southwest after sunset. The mag. +1.2, orange-coloured object 6.5º to the south of it is Mars.
Pete Lawrence “December’s going to be busy. I’m looking forward to watching the Geminids this year as the Moon will be new and the sky really dark. Then there’s Jupiter: what a sight that will be around opposition.”
WEDNESDAY
The almost full Moon makes a close pass of the planet Jupiter in the early hours. At 01:30 UT both bodies will be less than 1º apart as measured centre to centre.
BINOCULARS 10x50 recommended PHOTO OPPORTUNITY Use a CCD, webcam or standard DSLR SMALL SCOPE Reflector/SCT under 150mm, refractor under 100mm
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SATURDAY Jupiter’s Great Red Spot is centrally placed on the planet just before 23:00 UT.
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.
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DON’T MISS... 3 TOP SIGHTS Geminids WHEN: 12/13 and 13/14 December, all night
IT’S TIME FOR the annual Geminid meteor shower once more and this year the conditions are set for a dramatic show. There are many factors that affect the visibility of a meteor shower, but the two most prominent are the weather and the Moon. We can’t do anything about the weather, but the timing of the Moon is predictable. This year the shower’s peak occurs on 13 December and the Moon is new on that day too. This means that moonlight is not going to factor at all this year. The Geminids result from the debris field strewn
along the orbit of a rather strange object known as 3200 Phaethon. Rather than being classified as a comet – the source of most meteor shower debris – 3200 Phaethon is what’s known as a Palladian Asteroid, meaning that it is part of a family of asteroids associated with the main belt asteroid 2 Pallas. 3200 Phaethon has the distinction of being the named asteroid that passes closest to the Sun. At perihelion (closest approach), it moves within less than half of Mercury’s perihelion distance. Its orbit is more like that of a comet than
At its peak the shower should unleash more than 100 meteors per hour
an asteroid yet no cometary activity has been seen from it. Nevertheless, Earth passes through the debris field left around the orbit of 3200 Phaethon in mid-December, resulting in the Geminids meteor shower. The point in the sky that the meteors appear to emanate from is known as the radiant. In the case of the Geminids it lies fairly close to mag. +1.9 Castor during peak activity.
M35
5 Dec 10 Dec 13 Dec (peak)
Geminids radiant
GEMINI ε
15 Dec
20 Dec
α
Pollux
Castor
γ
β
PETE LAWRENCE X 4
δ
With no glare from the Moon to spoil the view, this year’s Geminid shower should be a particularly good one
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!
NEED TO KNOW
Meteors appear when particles of dust collide with our atmosphere at high speed. These particles are tiny, typically no bigger than a grain of sand.
The altitude of the radiant is another important factor that affects the number of meteors seen during a shower; for the Geminids this reaches its highest point in the sky, about 70º degrees, at around 02:00 UT. The peak zenithal hourly rate of 100-plus meteors per hour is predicted for 23:30 UT on 13 December. An all-night session through the nights of 12/13 and 13/14 December should yield some really impressive meteor activity, especially considering that maximum rates typically persist for about a day. To watch the Geminids all you need to do is wrap up warm, make yourself comfortable by lying on a sunbed or similar and keep watch at an altitude about two-thirds of the way up the sky. Direction isn’t important, but we’d suggest the Orion region until 2am, then Leo for the rest of the night. Geminids are medium speed meteors and often bright, making them ideal targets for meteor photography.
THE SKY GUIDE DECEMBER 51
Mercury, Venus and the Moon in the morning WHEN: 10-12 December between 06:00 UT and sunrise.
A TRIO OF planets and the Moon grace the December morning sky. Brilliant mag. –3.9 Venus sits between mag. –0.3 Mercury and +0.8 Saturn on 3 December low in the east just after 06:00 UT, taking the guise of an Orion’s Belt of unequal brightness. Venus moves away from Saturn over the following days, but the two planets are still only 6º apart on the morning of 10 December. This is when the Moon joins in the display – its delicate waning crescent (13% lit) appears 5º to the south of Saturn. By the following morning the waning crescent Moon – now just 6% lit – sits 4º to the southwest of Venus. The Moon should be showing earthshine at this time – the dark portion glowing due to reflected light from the Earth – and this should make the scene even more striking. On the morning of 12 December, the waning crescent Moon has dropped to 1% lit and is to the south of mag. –0.5 Mercury. It should still be relatively straightforward to pick out our satellite close to the southeastern horizon just before sunrise. The best time to try and do so is around 07:00 UT. After this date the Moon moves on, leaving Mercury, Venus and Saturn behind. Mercury and Venus continue moving towards the Sun while Saturn drifts farther to the west. On 21 December, look out for
20 Dec
Saturn
15 Dec
10 Dec 5 Dec
Moon 10 Dec
1 Dec
Venus 1 Dec 5 Dec
Mercury
Moon 11 Dec
10 Dec
1 Dec 5 Dec 10 Dec 15 Dec
Moon 12 Dec
15 Dec 20 Dec 25 Dec
Antares
30 Dec
30 Dec
SE There’s nothing astronomically significant about chance line-ups, but they still look pretty spectacular
a cosmic triangle formed by mag. –0.4 Mercury, mag. –3.9 Venus and mag. +1.0 star Antares (Alpha (a) Scorpii) at around 07:00 UT, again low in the southeast. Mercury starts to move faster towards the Sun than Venus from here on and soon leaves the brighter planet behind. Despite this, little Mercury should remain visible
until the end of the month given good weather and a flat southeastern horizon.
!
NEED TO KNOW
The zenithal hourly rate (ZHR) of a meteor shower is the expected number of meteors seen under perfect conditions with the radiant point of the shower overhead.
The Moon moves in front of M67 WHEN: 3 December from 22:45 UT until 02:00 UT
LUNAR OCCULTATIONS OF faint stars are not that uncommon, but those of whole star clusters are less frequent. On the night of 3 December, look out for the waning gibbous Moon (75% lit) moving towards mag. +6.9 open cluster M67 in the constellation of Cancer. Viewing this event isn’t going to be easy, since the Moon will be rather bright and the cluster is fairly faint, but it’s still worth looking for if you have clear skies. Use a medium magnification and look at the western, fully illuminated edge of the Moon from 22:45 UT onwards. You
should be able to make out some of the cluster stars quite close to this edge. Keep watching and the Moon will slowly but surely block the light from the stars as it moves relative to the background sky. M67 will start to reappear from behind the dark, trailing edge of the Moon at around 01:00 UT. As with all such events, the exact timings depend on where you live in the UK, so allow a good 30 minutes either side of the times suggested to make sure you see the start and end of the occultation.
Lunar occultations of entire open clusters aren’t that common, so don’t miss out
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THE PLANETS Pick of the month
AURIGA Pleiades Elnath
JUPITER BEST TIME IN DECEMBER:
Jupiter
3 December, 23:30 UT ALTITUDE: 58º LOCATION: Taurus DIRECTION: South
31 Dec Moon (morning of 26 Dec)
1 Dec
RECOMMENDED EQUIPMENT:
Aldebaran
3-inch telescope or larger
Hyades
V
TAURUS
FEATURES OF INTEREST:
Atmospheric belts and features, Great Red Spot, moons JUPITER IS DOMINANT this month, reaching opposition on 3 December. It’s hard not to be impressed by the sight of this mighty planet shining down on you from upon high. Located in Taurus, Jupiter reaches the dizzy altitude of 58º as seen from the centre of the UK. At mag. –2.6, it should be an incredible sight with the naked eye alone, but a telescope will reveal more detail on the Jupiter dazzles, even when faced with the glare of the Moon
ORION Jupiter’s mighty 47-arcsecond-wide disc lies close to the Hyades open cluster during December
provide the information you need to planet’s disc. The first thing you’ll notice identify these less prominent features. is that the disc isn’t round, but squashed Jupiter’s moons are a source of pole to pole. This is due to the gas giant’s rapid rotation period of less than 10 hours. fascination too. They can occasionally If the seeing is good and you’ve allowed be seen passing in front of the planet Viewed from : toLo caltim Field f view: andM agnituthis des:happens 6.2 5.2 4they .2 3.2 2.2 1cast.2 when can your scope cool fore: an hour orotwo, Staron Jupiter’s disc; at other Central British 35∞ shadows the planet can22:45:00 offerIsles up a wealth of 00' 00.0" Multiple star as they 02∞ 30' 00.0" 2012/11/30 WtheAzimuth (∞): 148.6809∞ times they may disappear detail. Most evident are North and (∞): 54∞ 00' 00.0" JD 2456262.45 N Altitude Variable +55.1552∞ star move into Jupiter’s own shadow. South Equatorial Belts. These are rarely With an apparent diameter of smooth and contain all manner of 47 arcseconds, Jupiter really is both atmospheric disturbances to tantalise the king of planets and the king of the eyes. Other less prominent belts also detail this month. With the other make themselves known after you’ve planets poorly placed, it certainly been staring at the planet for a while won’t disappoint! – the observing guides on the coverdisc
PETE LAWRENCE X 2, JUPITER’S MOONS ILLUSTRATION: ANDREW DUNCAN
How the planets will appear this month The phase, tilt and relative sizes of the planets in December. Each planet is shown with south at the top, to show what it looks like through a telescope
MERCURY 1 DECEMBER
VENUS 15 DECEMBER
URANUS 15 DECEMBER
MERCURY 15 DECEMBER MARS 15 DECEMBER MERCURY 31 DECEMBER
skyatnightmagazine.com 2012
SATURN 15 DECEMBER JUPITER 15 DECEMBER
0”
10”
NEPTUNE 15 DECEMBER
20” 30” 40” ARCSECONDS
50”
1’
THE SKY GUIDE DECEMBER 53
MERCURY
SATURN
BEST TIME IN DECEMBER:
BEST TIME IN DECEMBER:
4 December, from 06:30 UT ALTITUDE: 6º and rising LOCATION: Libra DIRECTION: Southeast Mercury is a morning object reaching greatest western elongation on 4 December, when it will be separated from the Sun by 21º. At elongation the planet shines at mag. –0.4, rising two hours before the Sun. Venus joins Mercury in the second week of December. On the 11th, look for a slender crescent Moon (6% lit) nestled close to Venus. From 07:00 UT, mag. –0.5 Mercury should be visible to the left of the pair. Mercury’s brightness remains similar through December, but the planet eases back towards the Sun by month end. VENUS BEST TIME IN DECEMBER:
1 December, 06:00 UT
ALTITUDE: 8º LOCATION: Libra DIRECTION: Southeast
Venus gets closer to the Sun this month but remains easy to see: look to the southeast as dawn begins, it’s hard to miss! You can see the planet pair up with the waning crescent Moon (6% lit) on the morning of the 11th. At the same time you’ll be able to see mag. +0.8 Saturn above and right of Venus and mag. –0.5 Mercury close to the horizon to the lower left. MARS BEST TIME IN DECEMBER:
31 December, 16:30 UT ALTITUDE: 7º (low) LOCATION: Capricornus DIRECTION: Southwest Mars isn’t a great telescope target at the moment, being very small and quite dim at mag. +1.2. However, it’s visible to the naked eye through the month. Head out at around 16:30 UT and look close to the southwestern horizon.
31 December, 06:20 UT
ALTITUDE: 22º LOCATION: Libra DIRECTION: South-southeast
Saturn is a morning object all month, slowly but surely climbing higher in the sky before dawn starts to take hold. At the start of December it’s 5º to the northwest of Venus, appearing somewhat dimmer at mag. +0.8. A slender waning crescent Moon (13% lit) lies to the south of Saturn on the morning of the 10th.
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 DECEMBER WEST EAST
DATE
1 2 3
URANUS BEST TIME IN DECEMBER:
1 December, 19:20 UT
ALTITUDE: 38º LOCATION: Pisces DIRECTION: South
Uranus reaches its highest point in the sky just after 19:00 UT at the start of December. The mag. +5.8 planet is due south and right at the threshold of naked-eye visibility, but binoculars will reveal it easily. Through a telescope its 3-arcsecond disc looks distinctly green. At the end of the month Uranus reaches its highest point in the sky as darkness falls, though the sky will still have a bit of residual brightness at this time. NEPTUNE BEST TIME IN DECEMBER:
1 December, 19:10 UT
ALTITUDE: 25º LOCATION: Aquarius DIRECTION: South
Binocular object Neptune is due south as darkness falls at the start of December. At an altitude of 25º this is a great time to grab a final view of the Solar System’s outermost planet before it drifts west into the evening twilight. You’ll need a scope to see its tiny 2-arcsecond, blue-hued disc.
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
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 31 8 7 6 5 4 3 2 1 0 1 2 3 4
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arcminutes
Jupiter
Io
Europa
Ganymede
Callisto
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On other dates, use the interactive planetarium on our website at www.skyatnightmagazine.com/interactive-planetarium
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WEDNESDAY THURSDAY 5
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CHART CONVERSION BY PAUL WOOTTON
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Times are given for the centre of the UK unless otherwise indicated.
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01 Dec 2012
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The Sun and Moon this month
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1. HOLD THE CHART so the direction you’re facing is at the bottom. 2. THE LOWER HALF of the chart shows the sky ahead of you. 3. THE CENTRE OF THE CHART is the point directly over your head.
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THE SKY GUIDE DECEMBER 55
CONSTELLATION NAME
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DEEP-SKY TOUR With Steve Richards
There’s more to the constellation of Perseus than the famous Double Cluster ✓
Tick the box when you’ve seen each one
A 6- to 8-inch telescope at very low magnification, fitted with an ultra high contrast or hydrogen-beta filter, will begin to reveal the vast cloud of hydrogen gas, but you can only see the shape of the US state of California in long-exposure images. SEEN IT
3
The California Nebula glows because the gases within are being ionised by a nearby star – possibly Menkib
4
5
CHART: PETE LAWRENCE, PICTURES: STEVE RICHARDS
1
2
CALDWELL 24
We start this month’s tour with a spiral galaxy, catalogued by Patrick Moore, that lies in the heart of the Perseus Cluster. Caldwell 24 (also designated NGC 1275) is one of the brightest members in this cluster of galaxies, although it is easy to mistake it for nearby NGC 1272 as the pair are within +0.1 magnitudes of one another. To find the galaxy, sweep 2.25° northeast from mag. +2.1 eclipsing binary Algol (Beta (β) Persei). A 10-inch or larger telescope will reveal a dozen or more galaxies, with the greatest concentration being to the southwest of the field of view. SEEN IT
THE CALIFORNIA NEBULA
Hop southeast to mag. +4.0 star Menkib (Xi (ξ) Persei), then sweep north by about 1° to find this rather elusive emission nebula, catalogued as NGC 1499. Appearing as a pale grey wisp of nebulosity, the California Nebula was discovered by Edward E Barnard in 1885 using the 6-inch Cooke refractor at Vanderbilt University.
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NGC 1582
This pretty open cluster is just under 0.5º across, with an elongation in an east-west direction. Although it lies right in the band of the Milky Way, it still remains well detached from the background stars. There are a dozen or more brighter stars with magnitudes greater than mag. +10.0 in a snaking line, with numerous fainter stars in attendance. A 6- to 8-inch telescope at 60x magnification will reveal several dozen stars in total. Hop 11° northeast from the California Nebula to mag. +5.3 star 59 Persei, then turn 90° and sweep to the west by 1.8° to find the cluster. SEEN IT
NGC 1528
Shuffle the numbers around a little and you’ll have our next object, open cluster NGC 1528. Hop northwest to mag. +4.1 star Mu (μ) Persei, then northwest to mag. +4.3 star Lambda (λ) Persei. NGC 1528 lies 1.7° to the northeast. The cluster is visible to the naked eye as a slightly fuzzy ‘star’ under dark skies, though a 3.5-inch telescope will reveal its true nature, showing 50 or so member stars. There are several patterns of stars within, with chains and small groupings aplenty. Increasing the aperture to 10 inches will increase the star count to over 90, most of which are clearly separate from the background. SEEN IT
MELOTTE 20
Open cluster Melotte 20 is a wonderful sight in binoculars or a rich-field telescope at low power – up to 50 stars will be visible through either. Find it by scanning west about 8º from NGC 1528 to mag. +1.8 star Mirphak (Alpha (α) Persei), the brightest member of the cluster. From a dark location, you should be able to detect the gentle haze of unresolved stars surrounding white-yellow Mirphak with the naked eye. The cluster is rather loosely scattered with a total population of around 100 stars, so there is plenty to enjoy – look for a particularly prominent S-shaped snake of bright stars leading from Mirphak. Although not a cluster member, the orange mag. +4.4 star Sigma (σ) Persei adds a lovely splash of colour to the wide-field view. SEEN IT
STRUVE 331
Our stop this month is delightful double star Struve 331. It’s comprised of a pale, lemon-yellow mag. +5.2 primary with a pale blue-green mag. +6.6 secondary to the east, designated SAO23763 and SAO23765 respectively. This is not a binary star, just a chance optical alignment. Despite their relatively soft individual colours, the pair contrast with one another very well and, at a separation of 12.1 arcseconds, they are easily split in a 4-inch telescope. To find the double, head northwest from Mirphak towards mag. +3.8 star Tau (τ) Persei. Struve 331 is just over 1° short of this stellar body. SEEN IT
+60°
05h
04h
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Berkeley 11 NGC 1582
NGC 1169
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52
NGC 956 NGC 1161
NGC 1186
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04h
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SKETCHING With Carol Lakomiak
Crystal Ball Nebula NEED TO KNOW STEP 1 Study the nebula for a while to determine its size. Once you’ve got a good idea, coat the tip of a blending stump with B graphite and draw the nebula in the centre of your sketching circle using small circular motions. Add the nebula’s central star using a B pencil.
NAME: The Crystal Ball Nebula, NGC 1514 TYPE OF OBJECT: Planetary nebula CONSTELLATION: Taurus RA: 04h 09m 17s DEC: +30° 46’ 33” TIME TO SKETCH: 5-15 December, 6am till 11pm UT EQUIPMENT: 6- to 8-inch reflector, optional OIII or ultra-high contrast filter, B pencil, blending stump
SKETCHES: CAROL LAKOMIAK, LUNAR FEATURE: PETE LAWRENCE
FIELD OF VIEW: 40 arcminutes; 76x magnification
William Herschel discovered the Crystal Ball Nebula, NGC 1514, in November 1790. It’s a planetary nebula that can be found in northern Taurus, almost 3.5º west-southwest of mag. +2.8 star Zeta (ζ) Persei. We now know that a planetary nebula is a glowing shell of gas and plasma blown off by a dying star. But at the time this one was discovered, it was believed that nebulae were clusters of unresolved stars. It was perfectly natural that Herschel should think the same of NGC 1514 – but there was something different about this one. He described it as “a star of about 8th magnitude with a faint luminous atmosphere, of circular form... the atmosphere is so delicate, faint and equally throughout... that there can be no surmise of its consisting of stars”. He didn’t know what he was seeing, but he knew it wasn’t star glow. The sketching tool we’ll use to draw the nebula is called a blending stump. It’s a tightly rolled piece of paper that looks like a pencil, and it’s held like one. A blending stump gently pushes graphite into the paper’s texture and produces a soft, smoky look, which is exactly what we need for skyatnightmagazine.com 2012
this sketch. If you apply too much graphite and the nebula looks a bit intense, use a kneadable eraser to ‘dab’ some off. The anchor stars drawn first are usually the brightest in the field. Their job is to create a stellar backdrop to refer to while sketching, which will help you to place the rest of the stars. If your scope isn’t equatorially mounted, they double as framing stars that will help you re-centre the nebula in the eyepiece as Earth’s rotation causes it to drift out of view. Since the central star of NGC 1514 is mag. +9.4, it’s used as an anchor star in this sketch. Our brains help us to see shapes in star fields, the most common being the triangle. These shapes are useful when it comes to judging angles and distances between stars. But you’ll also see chains of stars reminiscent of Eridanus and Draco, constellations created long ago with the same eye-brain coordination that showed our ancestors mythical shapes in the night sky. After you’ve completed your sketch, convert it to a negative image in an editing program to make it look like the view you actually saw in the eyepiece.
STEP 2 Draw your anchor stars with a B pencil. To help you place them as accurately as possible, use the familiar shapes they form as guides. Notice that a star can be part of more than one shape and that the nebula’s central star can also be used as an anchor star.
STEP 3 To populate the star field, look around each anchor star and determine if it can be included in a familiar shape or a recognisable pattern. For example, there’s a triangle of stars to the upper right and two star chains, one running along the bottom the other to the upper left.
THE SKY GUIDE DECEMBER 59 N
TACITUS
THEOPHILUS
E
CYRILLUS MARE NECTARIS CATHARINA
POLYBIUS
FERMAT
Altai Scarp
PONS ALTAI SCARP
TYPE: Scarp SIZE: 298 miles (480km) long AGE: Between 3.92 and 4.55 billion years old LOCATION: Latitude 23°E, longitude 24°S BEST TIME TO OBSERVE: 2, 3, 19 and 20 December RECOMMENDED EQUIPMENT: 4-inch reflector
The Altai Scarp can be easily found by using the much more conspicuous Theophilus crater trio
MOONWATCH With Patrick Moore “It is interesting to look around to see how many ‘mountain ranges’ are not true mountains at all, but scarps similar in nature to the Altai formation” THE ALTAI SCARP is marked on many of the earliest Moon maps as the Altai Mountains. Taking a general view of the region it does look as if the Altai Scarp is mountainous and, superficially, it does look like a mountain range, particularly when it is casting a shadow. But it is actually part of the ring system around the Mare Nectaris. Indeed, the Mare Nectaris itself is the central part of a lunar basin that has been completely flooded with lava. The Altai Scarp simply makes up a well-defined continuation of the rim of the mare’s basin. The Altai Scarp begins near Crater Catharina, a large feature named after
Saint Catherine of Alexandria that has been considerably damaged by meteoroid impacts. It is one member of a celebrated trio of craters, the others being Crater Theophilus and Crater Cyrillus. Altai extends south past Crater Fermat and almost as far north as Crater Tacitus. It is easy to find the scarp because the Theophilus trio cannot possibly be missed. There is much to be learnt by examining these three craters. Theophilus itself is the youngest, since it intrudes into Cyrillus, which itself intrudes into Catharina. Lying north of the northern end of the scarp you’ll find Tacitus, a prominent and well-formed crater, 40km across,
named in honour of the famous Roman historian. The scarp itself does not extend past Tacitus, though under suitable lighting it gives the impression of doing so. In the region south of the Theophilus trio, look for the Crater Polybius to one side of the scarp and Craters Fermat and Pons on the other. The height difference between the east and west of the Altai Scarp can be conspicuous. The scarp rises high above the general level of the ground to the east, but only very slightly above the levels found to the west. It amounts to something like 1,000m. Having studied the surroundings of the Altai Scarp, it is interesting to look around to see how many ‘mountain ranges’ are not true mountains at all, but scarps similar in nature to the Altai formation. It’s also interesting to note which of the smaller ‘seas’ are nothing more than the deepest parts of much larger basins; there are quite a number of them. The whole area south of the Altai Scarp is decidedly rough, even by lunar standards, and there is little level ground anywhere. A small or medium telescope is adequate to identify the Theophilus trio and the Altai Scarp itself. skyatnightmagazine.com 2012
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ASTRO PHOTOGRAPHY With Pete Lawrence
Image Jupiter in infrared Recommended equipment Monochrome camera without built-in blocking filter, RGB and infrared-pass filters, filter wheel
FILTERS ARE WONDERFULLY useful things, but they often have quite confusing names. Consider the filters used in everyday circumstances. The pollen filter in your car is designed to let air through but catch any grains of pollen that may be present, preventing sneezing fits among hay fever sufferers. A water filter, on the other hand, is designed to let water pass but remove any impurities it may contain. There’s confusion here: one filter name describes the thing that is being blocked, while the other describes the thing that is allowed to pass. A similar situation occurs in astro imaging where filters are used to restrict or pass specific wavelengths of light. One source of confusion is the infrared filters used for lunar and planetary imaging. Without qualification, it’s not clear whether an infrared filter passes or blocks infrared light.
In astronomy we avoid this problem by adding the words ‘pass’, ‘blocking’ or ‘cut’ to the filter name. An infraredpass filter allows the infrared part of the spectrum through, but blocks all other wavelengths of light. Conversely, an infrared-blocking filter (sometimes called an infrared-cut filter) stops infrared light, allowing just the other wavelengths through. Both have applications for lunar and planetary imaging, but first a word of caution – you can’t use infrared-pass and infrared-blocking filters together. If you fit both onto your gear at the same time you won’t be able to see anything. The pass filter will only transmit infrared light, while the blocking filter will stop that going through too. It sounds like a silly thing to do but believe me, if you have both types it’s an easy mistake to make.
An infrared-blocking filter is a useful and inexpensive add-on for a high frame rate imaging camera, and can be used with both monochrome and colour devices. Its role is to stop infrared wavelengths from entering the camera; this is useful because imaging sensors tend to be quite sensitive to this light. Without the blocking filter, infrared can cause features to appear bloated, less distinct and have their colour balance skewed. Certain cameras have infrared-blocking filters incorporated into the optical window that covers the imaging sensor. Similarly some colour filters, like those used for LRGB imaging, may have infraredblocking built in. Remember the word of caution from earlier? If your camera has an infrared-blocking filter built in and you fit an infrared-pass filter to it the effect is the same – you’ll see nothing. If you’re in any doubt as to whether your kit has an infrared-blocking filter already fitted, ask your astronomical supplier for advice before purchasing additional filters. If you don’t have one built-in, you can always screw one into the nosepiece of your camera.
A study in scarlet Cameras that don’t have built-in blocking filters can also be used with an infraredpass filter. There are several reasons why you’d want to do this – one is that longer wavelengths in the red and infrared part of the spectrum tend to be less affected by atmospheric seeing, so views that shake like jelly can be made more stable by adding an infrared-pass filter.
ALL PICTURES: PETE LAWRENCE
How to improve contrast in your shots of Jupiter
STEP 1 Do a bit of research to check whether your camera is fitted with an built-in infraredblocking filter before buying any type of external infrared filter. If it is, you don’t need to purchase another infrared-blocking filter and an infrared-pass filter won’t help you. Certain LRGB filter sets also have infraredblocking built in, so check these too.
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STEP 2 The best camera for infrared-pass work is a high frame rate monochrome without a built-in blocking filter. Assuming your camera fits this bill, an infrared-pass filter will be a useful addition. One that passes wavelengths from 742nm onwards is ideal, but bear in mind that this will create a dimmer image – it’s best suited to scopes with apertures greater than 4 inches.
STEP 3 If you take colour images of the planets using RGB filters, consider investing in a filter wheel if you don’t already have one. Available in either motorised or manual versions, this accessory will make swapping between filters much easier. This is especially true for Mars, Jupiter and Saturn, which spin so fast that you need to keep imaging time to a minimum.
THE SKY GUIDE DECEMBER 61
The term ‘infrared-pass’ is usually qualified by stating the wavelengths or the start of the wavelength range allowed through. As an example, the Astronomik ProPlanet 742 infrared-pass filter only allows infrared light with wavelengths greater than 742nm through. Astronomik’s 807 version does the same, but from 807nm onwards. Baader Planetarium’s Methane filter is also an infrared-pass filter, but this one only lets through a narrow range of wavelengths centred on 889nm. For this particular filter, the narrow range of wavelengths passed, also called its ‘bandpass’, is just 8nm wide. This is what’s known as a narrowband filter. A methane filter is useful for imaging Jupiter. The methane present in its atmosphere appears dark through this filter, while regions where there’s less of the gas appear light. This is great for picking out active storms, including the famous Great Red Spot. Significantly less light is transmitted through an infrared-pass filter, so the resulting image will be dimmer. A 742nm image will appear dimmer than one taken through a standard filter, while the view through the 807nm narrowband filter will be fainter still. The methane filter is suited to larger instruments for this reason. But there are advantages to using a 742nm infrared-pass filter. It can enhance the contrast between features on a planet’s disc, producing sharp results, and Jupiter’s Galilean moons also shine brightly in the infrared. Using an infrared-pass filter can therefore help keep them visible as they pass in front of the planet’s disc.
STEP 4 So, you have your filter wheel fitted with RGB and the infrared-pass filters: set the wheel so that the R or G filter is in use. Line up your scope up as normal and adjust the planet’s position so that it sits more or less centrally on the chip. Focus the image. Now rotate the filter wheel so that the infrared-pass filter is being used. Re-focus as accurately as possible.
This shot of Jupiter was taken using a 742nm filter, granting a sharper result
Key technique COUNTERING EARTH’S ATMOSPHERIC WOBBLES
An infrared-pass filter can give a more stable, more detailed and more contrasted rendition of Jupiter. The technique also works well for Mars and Saturn. The big advantage of using this type of filter is that the longer wavelengths found at the red end of the spectrum are less affected by atmospheric seeing than those at the blue end. Like the high frame rate camera, the infrared-pass filter is another important tool in reducing the wobbles and distortions that Earth’s turbulent atmosphere introduces to spoil our views of the night sky.
Send your image to:
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STEP 5 The camera settings you use will depend on the camera model and the light gathering ability of your telescope. If you’ve got a small scope, don’t use any optical amplifiers (eg Barlow lenses) to start out as these may make the image too dim to be useful. Increase exposure and gain, and reduce frame rate to maintain a good saturation level of around 80-90 per cent.
STEP 6 One advantage of using an infrared-pass filter is that details on the planet’s disc will typically look well contrasted. This helps post-capture processing applications such as RegiStax, AviStack or AutoStakkert! by giving them something to work with. Process your infraredpass captures in the same way that you would process any other high frame rate capture.
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Apollo 8 commander Frank Borman saw Earth emerge over the lunar horizon like this; he said it was the most beautiful thing he had ever seen
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Apollo 17’s night launch remains an unrivalled spectacle
or the first minute of each Apollo mission, the experience was better on the ground. To the astronauts sitting high up in the nose of the Saturn V rocket, the moment of launch was signalled by modest vibration and a rumbling noise far below. From the viewing stands at Cape Canaveral, in contrast, the raw power of the rocket was evident in the fire pouring from its engines, billowing exhaust clouds and bone-shaking waves of sound, as if a furious deity was at work. Forty years ago, Apollo 17 – the final manned mission to the Moon – served up the greatest launch spectacle of all. It departed at night, the flames from the Saturn V flooding the horizon with light, turning darkness into day. Watching from a cruise ship anchored offshore, science-fiction author Isaac Asimov observed that “it was useless to try to speak, for there was nothing to say”. It was an ambiguous moment in the history of human spaceflight. Those attending the launch might have been overwhelmed by what they witnessed, but the American people – on the whole – were not asking for a repeat performance. A poll conducted after the
THE SPIRIT OF APOLLO DECEMBER 65
A new sense of place The anticipation that US astronauts might return from their missions transformed, with a new understanding of their relation to Earth and the Universe – and even to God – was part of popular thinking about spaceflight throughout the Space Age. In February 1962 John Glenn, the first American to orbit Earth, appeared before a congressional committee and was asked if his flight aboard Friendship 7 had been a spiritual experience. “I was wondering,” said one senator, “whether you felt that God was up there as well as down here, and that in Him you lived and moved and had your being?” There was nothing eccentric about such a line of enquiry. The space programme integrated flight and exploration, and the annals of both endeavours are full of instances when pioneering individuals had experienced epiphanies, visions or other strange sensations. After Charles Lindbergh successfully made the first non-stop flight from New York to Paris in 1927, he reported consorting with ghostly presences moving through his cabin. In the 1950s, as jet aircraft became capable of ascending to the upper troposphere, clinical research pointed to the existence of a ‘break-off phenomenon’, experienced by military pilots. It was characterised
Þ Early astronauts were all military test pilots, who NASA believed had the mental mettle to cope with the rigours of space travel. Left to right: Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, Deke Slayton
SELECTING THE RIGHT STUFF Five things NASA did to ensure the mental stability of its astronauts
Þ Mercury astronaut Scott Carpenter during centrifuge training 1 In its first and second astronaut selection rounds, in 1959 and 1962, NASA insisted that candidates were experienced test pilots, attuned to the conditions of high altitude flight and psychologically reconciled to the hazards involved in aeronautical experimentation. The requirement was dropped in subsequent rounds.
2 The first selection round tested the candidates’ responses to stressful conditions, including sudden acceleration, vibration, loud noise, and extreme heat and cold. Each was confined to a dark room to assess their tolerance for isolation. 3 Once selected, astronauts underwent a training programme designed to limit the environmental unknowns that might confront them during missions. They were repeatedly whirled around a centrifuge, experienced moments of weightlessness during parabolic flights and spent many hours enclosed in mock capsules. 4 The first Americans to go into space, Alan Shepard and Gus Grissom, were examined by a psychiatrist on the morning of their flights. 5 Space scientists recommended that, throughout each flight, the astronauts should be kept busy and stay in constant communication with Earth to prevent their minds taking an inward, pathological turn. There were many operational reasons to keep the astronauts hard at work, but they were reinforced by such clinical concerns.
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NASA X 4
Apollo 17 mission revealed that most Americans wanted their country to ‘do less’ in space. Taxiing men to and from the Moon seemed a quixotic use of resources in tough economic times. Yet this was also a moment when the experiential, philosophical aspects of the programme – aspects that evaded cost-benefit accounting – were receiving renewed attention. In particular, commentators proposed that spaceflight had yielded a spiritual return, in its effects upon the astronauts and in the messages that they, in turn, sought to communicate to others. “The Apollo veterans have become poets, seers, preachers,” Time magazine asserted. Many of them, it said, had been “profoundly moved by their experiences away from Earth”.
as a profound feeling of isolation from Earth. The pilots perceived themselves as somehow losing their connection with the world. Much of what passed for early ‘space science’ took the form of anxious speculations about how astronauts might respond psychologically to the conditions of spaceflight: the separation from Earth, the isolation from other men. A range of isolation experiments were conducted, some of which involved prolonged confinement in a space-capsule simulator. Almost routinely, those who participated in these experiments started to hallucinate. As a result, in the astronaut selection process for its initial manned spaceflight programme, NASA showed a marked preference for candidates whose personalities appeared to be well-armoured against spontaneous transformations. For obvious operational reasons, it did not want any astronaut, in the course of his mission, to start having visions. The candidate pool was restricted to military test pilots, a group of people who had already demonstrated an ability to withstand stresses comparable to those likely to be encountered in space. Psychological stability, noted an official review, was “the most important consideration in evaluating a candidate”. Even after the selections had been made, the successful candidates, now competing for mission assignments, were careful to conform to the ideal: reticent, rational and stimulated more by the operational challenges of the space age than by >
66
An awe-inspiring view of the Universe was not of primary concern to the designers of NASA’s cramped spacecraft
> the opportunities it presented for
markedly new experiences. To depart from this norm – to openly anticipate becoming filled with wonder when aloft in the heavens – was to shrink the chances of being trusted with an actual mission. In space itself, astronauts continued to observe the rule: their reports on new sights and sensations tended to be dressed in self-conscious calm. But the deficits of excitement in astronaut responses were not a product of NASA culture alone. Because of bleary windows and the attitude of the spacecraft, it was frequently impossible for those inside to experience the full visual majesty of the cosmos. Nor did they have much opportunity to appreciate the view outside the capsule. During spacewalks and moonwalks, the pace of work was constant. Gemini 10 pilot Michael Collins imagined what he might have said about walking in space: “‘I found God outside my spacecraft.’ Wrong, I didn’t even have time to look for Him.”
Þ Earth as seen from Apollo 11, a bright marble in the blackness of space
Spacewalking astronauts were kept so busy by NASA they had no time to appreciate their surroundings
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Yet, despite their unrelenting attention to operational needs and the emotional reticence that marked their corporate style, it was possible for astronauts to sense some movement of the spirit. Towards the end of Apollo 9’s Earth orbital mission, lunar module pilot Russell Schweickart finally had the chance to gaze out of the window. He looked first for the ‘friendly things,’ such as his home city, Houston – “You identify with that, it’s an attachment.” Gradually, with each passage around the world, the locus of attachment widened. Schweickart found himself ‘identifying’ with North Africa. By the end of the mission, his sense of connection had come to encompass the whole Earth. “And somehow you recognise,” he stated, “that you’re a piece of this total life.”
New perspectives Schweickart was unusual: similar epiphanies of belonging were experienced by other Apollo astronauts, but usually only after they departed Earth orbit for the Moon. On the journey out, as Earth shrank in size and the blackness around it grew, its blue and white colours became more brilliant. This was, Collins recalled of his flight on Apollo 11, “a sobering, almost melancholy, sight”. Earth seemed beautiful and delicate precisely because, from a distance, it was clearly surrounded by annihilating space. The lesson was reaffirmed by arrival in lunar orbit, for the Moon was grey, cratered and dead, a desolating vision of what could happen to a world. And so when their capsule circled back around to the scene of a lambent Earth rising above a barren lunar landscape, it was not uncommon for astronauts to experience a powerful rush of emotion. “It was the most beautiful, heart-catching sight of my life,” remembers Apollo 8 commander Frank Borman. Collins described the small blue sphere climbing over the craggy horizon as “home and voice for us”; earthrise coincided with the restoration of radio contact with mission control, a reminder that there was the only source of comfort and aid available to the astronauts as they traversed the heavens. Later, as the return journey began, Collins looked at Earth “in wonderment, suddenly aware of how its uniqueness is stamped on every atom of my body”. But then “I looked away for a moment and then it was gone. I couldn’t find it again without searching closely.” Apollo 14 lunar module pilot Edgar Mitchell also gazed through a window at Earth and experienced a fierce sensation of belonging. On Earth – “on that fragile little sphere” – was “all I had ever known, all I had ever loved and
THE SPIRIT OF APOLLO DECEMBER 67
Þ The Apennines rise behind Apollo 15’s James Irwin, whose trip to the Moon renewed his faith
and the molecules of the spacecraft itself were manufactured long ago in the furnace of one of the ancient stars that burned in the heavens about me.” And if every astronaut was made of the same stuff as the stars, there was nothing unnatural about spaceflight. For Mitchell, it was “an extension of the same universal process that evolved our molecules.” The human cosmos stretched into the infinite.
< Apollo 14’s Edgar Mitchell, like so many astronauts, felt a sense of belonging when he saw Earth from afar hated, longed for, all that I once thought had ever been and ever would be”. Yet what was forged in Mitchell’s grand epiphany was not a new identification with the Earth alone. Mitchell had studied physics at MIT and was well-acquainted with the recent empirical confirmation of Big Bang cosmology. Now, in an “ecstasy of unity”, as he coasted between the Moon and Earth, he arrived at an understanding of what this cosmology really meant: that everything was connected. Where Collins had felt Earth in every atom of his flesh, Mitchell perceived the Universe. “It occurred to me,” he wrote, “that the molecules of my body
For some Apollo astronauts, the Moon seemed a dull, unattractive place, but for others, it retained an aesthetic appeal – especially as later lunar missions ventured into more rugged and diverse terrain. It was in the Imbrium Basin, at the foot of the Apennine mountains, that Apollo 15 lunar module pilot James Irwin had a powerful epiphany. Irwin had always found most contentment in high, open places, during solo airplane flights or on mountain treks, where he felt close to the seat of the divine. To him, the lunar landscape seemed both familiar and providential. He sensed God’s presence around him, he wrote in his memoir To Rule the Night. A problem with a power generator was solved as soon as he prayed for guidance. The next day, Irwin spotted a strange, lightly coloured rock perched upon a base of grey stone. Later, the rock would be dated as being over four billion years old, close to the age of the Solar System itself. To Irwin, the placement of the rock – “it seemed to >
NASA X 5
The help from the hills
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68 THE SPIRIT OF APOLLO DECEMBER
LIFE AFTER SPACE Edgar Mitchell
Time in space: 9 days, 42 minutes Missions: Apollo 14, lunar module pilot Retired from NASA: 1972 Edgar Mitchell’s epiphany of universal connectedness convinced him that there was no fundamental divide between the realms of spirit and matter, religion and science. But how were these realms actually related? He devoted the next 20 years to exploring that question. Mitchell resigned from NASA in 1972 and founded the Institute of Noetic Sciences (IoNS) to foster the scientific study of consciousness, its power to affect matter and its capacity for transference without explicit communication. IoNS sponsored laboratory tests into the claimed psychokinetic and telepathic powers of a young Israeli magician, Uri Geller. The claim that Geller had achieved positive results in the experiments – results that seemed to defy conventional scientific explanation – precipitated a wave of public interest in parapsychology and made Geller an international celebrity. IoNS is still going. It is currently based at a 200-acre campus north of San Francisco and claims a membership of close to 30,000. There are not many Apollo programme spin-offs that can attest to the same durability or breadth of constituency.
Time in space: 12 days, 7 hours, 11 minutes Missions: Apollo 15, lunar module pilot Retired from NASA: 1972 Soon after his return to Earth, Irwin began to speak publicly about his conviction that God had been with him on the Moon, giving him guidance. His message proved popular. In 1972, following his retirement from NASA, Irwin established his own missionary foundation, named High Flight. He became a near-constant presence on Southern Baptist radio and television programming, and travelled widely in Asia and the Pacific, holding religious rallies and meeting with political leaders. By early 1973, Irwin was being described as the leading preacher on the US’s independent evangelical circuit. In April he suffered a serious heart attack, and his ministry was effectively grounded for the next two years. Although his health remained precarious, Irwin travelled to Mount Ararat in Turkey a number of times in search of Noah’s Ark, but no relic presented itself to him providentially in the manner of the four-billion-year-old rock on the Moon. Irwin died in 1991 following another heart attack. The High Flight Foundation continues its work, led by Irwin’s daughter, Joy.
> say, ‘here I am, take me’” – showed that God
had willed its discovery. Man on the Moon, he believed, remained within the horizon of divine care and concern. Returning to the lunar module for the final time, the sunlit Apennines before him, Irwin recited a favourite line of scripture: “I will lift up mine eyes unto the hills, from whence cometh my help.” He sensed the beginning of a deep change within him, a new confidence in the power of God.
NASA X 3, GETTY
The eye of the beholder Not every Apollo astronaut returned from their mission in the heavens with a new appreciation of the sacred. Whether or not an astronaut found God in space depended very much on what C S Lewis called ‘the seeing eye’ – who that astronaut was and what he already believed. Irwin was a case in point. Having long struggled with faith, Irwin seemed to be moving towards some
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James Irwin
Þ The rock discovered by James Irwin was dated at four billion years old and inspired his epiphany
kind of spiritual resolution even before his flight. The potential hazards of the mission served to concentrate his mind: “I wanted to be prepared in every way in case I didn’t come back,” he said. He joined a local Southern Baptist church, testified about his relationship with Christ and scheduled his baptism for after he returned from the Moon. But he could not yet attest to the sort of confirming experience of God’s presence that Southern Baptists – more than any other denomination – value most highly. What happened to Irwin on the Moon, therefore, was just what he needed to truly belong in the church he had chosen back on Earth. Sometimes, ‘the seeing eye’ saw precisely what it had been looking for. S ABOUT THE WRITER Kendrick Oliver’s third book, To Touch the Face of God: the Sacred, the Profane and the American Space Program, 1957-1975, will be published in March 2013.
70 1 Selecting Jupiter
PROJECT 1
Open WinJUPOS and select 'Program' from the main menu, then 'Celestial body' to open a list of all the bodies covered by WinJUPOS. We’re looking at Jupiter here, so click on the 'Jupiter' entry. If this is the first time you’ve used WinJUPOS for Jupiter it asks you to define a data directory. Simply create a folder with the name Jupiter and use that.
Find the positions and timings of Jupiter's features and the Galilean moons Despite Jupiter’s rapid rotation (it completes a spin in less than 10 hours), with WinJUPOS you can plan observations very accurately. The program is useful for checking the visibility of Jupiter’s Great Red Spot and its four largest moons. What's more, if you create your own map of Jupiter (as we’ll do in the next project) it can be used as a 'simulation texture' in this part of the program to check the visibility of current atmospheric features.
2 Bringing up information about Jupiter Click on 'Tools' in the main menu, then 'Ephemerides'. This brings up a window full of information about Jupiter. Use the input boxes and controls in the upper part of the window to define your location, as well as the date and time that you’re interested in. The time can be stepped up and down in increments of 1 and 10 minutes.
3 Ephemerides Ephemerides are tables of positional data for celestial bodies. In WinJUPOS, this information is divided up by tabs. It includes the planet's rise and set time, apparent diameter, altitude and the current longitude of the centre line of the disc. Jupiter’s atmosphere rotates at different speeds, creating three rotation ‘systems’ known as I, II and III, which is why there are three longitudes shown.
4 Moons The moon coordinates and moon ephemerides tabs give numeric information about the position and appearance of Jupiter’s four main moons, including their apparent size and visual magnitude. In addition, the moon coordinates tab also gives details about the position of the moons’ shadows on Jupiter’s disc. WinJUPOS also provides similar information for other major Solar System moons, including Saturn's Titan and Uranus's Ariel.
ALL PICTURES: PETE LAWRENCE
6 Options 5 Graphics tab The graphics tab provides a visualisation of the Galilean moons and their shadows. You can use the controls to the left of the graphic to zoom in and out of the view, or centre on Jupiter or any of the moons. Below these controls are several tick boxes; particularly noteworthy are 'Names' to help you identify the moons, and 'Texturing' which will show the visualisation with realistic textures.
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The options tab allows you to adjust the graphics viewing settings. For example, the Great Red Spot drifts in longitude over time. If you set the 'longitude of the left margin' (circled) of the default texture image to the Spot's current longitude (which you can find online), the graphics view will accurately represent where this feature is on the planet. This is especially useful for observation planning.
WORKING WITH WINJUPOS DECEMBER 71 1 Create an image measurement settings (.ims) file WinJUPOS requires images to be ‘measured’ (calibrated) before processing, so that the orientation and size of the planet’s disc are determined for a given date and time. Click 'Recording' in the main menu, then 'Image measurement...'. A new window opens. Within this, with 'Imag.' tab active, press F7 and select an image. Enter the time and date details of the image, then press F11. The program will try to outline the planet and make an .ims file.
PROJECT 2 How to make a map of Jupiter from your images There are many powerful functions lurking within WinJUPOS, including an option to create a map of a planet using your own images. WinJUPOS takes your images and blends them together, producing a map that can be displayed in a number of different ways, called projections. The process, detailed below, also introduces the image measurement settings file: a key component necessary to unlock several other powerful WinJUPOS operations.
2 Manual outlining If the automatic detection doesn’t work you can adjust the outline overlay manually. Use the arrow keys to move it, Page Up and Page Down to enlarge and shrink it, and N and P to rotate it in 1º degree increments clockwise and anti clockwise.
3 Saving the .ims file Press F2 to save the .ims file. The default filename reflects the image’s date and time. The image is ready for mapmaking once its .ims file has been created.
4 Creating the map To create the map, select 'Analysis' from the main menu, then 'Map computation'. Click the 'Edit' button on the top right and select 'Add'. Pick the .ims file from Step 3. Set the initial projection type to 'Cylindrical projection' and press F12 to create the map. You can change its size by altering the map width value.
5 Making the map from multiple images Repeat Steps 1-3 for your other images. Create each image’s map on its own, as described in Step 4, and adjust the From L and To L values to crop off unwanted dark edges. Images of a similar colour and tone give the best results, although brightness, contrast and gamma can be adjusted for each .ims file. When done, click 'Compile' to create the final map.
6 Experimentation Experimenting with the map options will produce different maps from the same .ims files. Polar projection, for example, gives you a result as if you’re looking down on one of the planet’s poles.
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PROJECT 3 How to make a rotation animation from your images Once you’ve used WinJUPOS to create a map of a planet, you can then feed that map back into the program in order to create a full rotation animation. This obviously works best when you have the entire disc mapped, but even partial mapping can produce some excellent rotation sequences, albeit with a few gaps. This feature really brings planetary imaging to life.
1 Creating the map Create a map of Jupiter using the step-by-step on page 71. If you want to use this map as a texture within WinJUPOS you’ll need to set a reference point for it. The Great Red Spot is ideal for this, so set the 'longitude of the left margin' to match the centre of the Spot (around 185º degrees in late 2012).
2 Graphics tweaks Click on the 'Page Layout' button in the map computation window. Deselect all options and choose a black map background if your images don’t cover the entire planet. Once done, hit 'OK' to compile the map. Click the disc icon in the upper left corner of the map window to save the finished map to your hard drive.
ALL PICTURES: PETE LAWRENCE
3 Applying the map as a texture Click on 'Tools', 'Ephemerides', then select the options tab. Click on the '…' button next to the texture image entry box and select the map graphic you’ve just edited and saved. Ensure the projection type matches that of the map you’ve made. For an authentic view, set the 'longitude of the left margin' to match that of the Great Red Spot, as in Step 1.
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4 Display the globe Click on the Graphics tab and make sure that 'Texturing' and 'Shading' are ticked but 'Names', 'C M + equator' and 'Grid' are clear. Your map image will now be mapped to Jupiter’s sphere. You can preview how the video will look by using the video-player forward and back controls. The double arrow button rotates the planet quickly, the single arrow button slowly.
5 Define the animation file
6 Create the animation
To create the animation, click 'Save image sequence'. This button is located above the upper-right corner of the graphic display and makes another window appear. Click on the '…' button next to the file name box and give your animation a title. Choose from either GIF or AVI output types. GIF is an animated stills format, AVI is a movie format.
There are various output settings; for simplicity, select a width and height of 300 pixels, deselect 'Incl. moons and their shadows' and tick 'One full rotation' to start. An increment of 1 minute is fine too. Click 'Compute' and WinJUPOS will create the animation. When done, WinJUPOS will offer to display the result using its own viewer.
WORKING WITH WINJUPOS DECEMBER 73 1 Captures There are many ways that you can apply de-rotation. The method here involves capturing several (repeating) RGB movie sequences for later de-rotation. Each filtered capture should be short, typically 60-90 seconds. Use short capture times for long focal lengths (8m or greater) as motion blur becomes more evident at longer focal lengths.
PROJECT 4 Using WinJUPOS to de-rotate planetary images If you image a fast-rotating planet – such as Mars, Jupiter or Saturn – over too many minutes your captures will show motion blur. This is a major issue if you’re capturing separate red (R), green (G) and blue (B) images that you want to combine for a final colour picture. WinJUPOS can de-rotate images, opening up the potential to use images taken over much longer periods than usual.
2 Processing Each RGB movie sequence needs to be processed using a registration-stacking program (for example, RegiStax, AviStack or AutoStakkert!). Only gentle wavelet sharpening should be applied. Save the final RGB images as uncompressed TIF files.
5 Combining de-rotated RGB images Select 'Tools', 'De-rotation of images'. Click the 'Edit' button and then 'Add' to add all of the de-rotated RGB .ims files generated in the previous step. Set the image destination directory. Finally, click 'Compile image' to generate the fully de-rotated, final colour image from all of your other RGB images. This step helps to reduce the noise in the final image, producing a higher-quality result.
3 Measuring Create an .ims file for each processed capture as described in the step-by-step walkthrough on page 71. It’s important to make sure that the date and time for each capture is entered accurately.
4 De-rotation Select 'Tools', 'De-rotation of R/G/B frames', then load your first set of RGB files. Click on 'Compile image' to generate the de-rotated RGB image. Click on the image measurement button and save the .ims file for the compiled image. Do this for all of your sets of RGB captures. It’s also possible to add a luminance channel – to improve image detail definition and contrast – at this stage.
6 Final tweaks Open the image compiled in the previous step in a graphics editor and apply any final tweaks to taste. Useful processes include a gentle application of unsharp masking, and levels and curve adjustments. S
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THE BIG QUESTIONS DECEMBER 77
THE BIG
In this occasional series, theoretical physicist Dr Mike Evans tackles the enduring questions of our Universe. In anticipation of next month’s big question about the Big Bang, we ask...
QUESTIONS How can space be curved? THINKSTOCK
T
hings can be curved. That’s an uncontroversial statement. I’m thinking of things like sheets of paper, metal rods or the surface of Earth. You can look at these things and judge whether they are curved or flat for yourself. It also seems fairly uncontroversial to say that empty space isn’t a thing; it’s just the gap between things. That makes the
idea of curved space sound ludicrous. But you’ve almost certainly heard the phrase uttered in connection with the theories of Albert Einstein. So, what does it mean? How can something that’s not there be curved? You might wonder whether this is some special technical use of the word ‘curved’, or just a metaphor to suggest it’s like a curved thing. No. You are
genuinely being asked to believe that the vacuum – the void in between things in space – can itself be bent. The correct response to this idea is, “Huh? What the...?”, and that’s a fair question. It would also be fair to ask, “Never mind it being curved. How can space – emptiness, nothingness – have any properties at all?” Let’s start with that question before we tackle the biggie. >
The Sun’s gravity keeps Earth in orbit; what seems to be a curved orbit through ordinary space is really a straight line through curved space
skyatnightmagazine.com 2012
78
100km
A round trip
REGION A
Drop-off point
THINKSTOCK X 4
Þ If you travel in a straight line, you can return to your starting point by retracing your steps, illustrating that space does have properties – in this case connectivity between Regions A and B
skyatnightmagazine.com 2012
100km
100km
> So you find yourself floating in space (it could happen: Virgin Galactic is now taking online bookings and spacewalks may be the next offering after a flight in SpaceShipTwo). You watch anxiously as Richard Branson’s dazzling grin vanishes into the distance, then activate your spacesuit’s jet pack and head out 100km forwards from the drop-off point. Knowing that you were initially stationary with respect to Earth and using an accelerometer (like the one in a smartphone) to keep track of any changes in speed, you can work out how far you have gone just by measuring the time since you set out. After 100km, you decide to turn around and return to the drop-off point, where you’ve belatedly arranged to rendezvous with Richard (lucky your phone was charged; shame he’s only got first-class tickets left). You know that, if you travel 100km back the way you came, you’ll be back at the drop-off point. But how do you know that’s the case? Take a look at the illustration above. Well, the bit of space you’re now in, Region B, is still connected to Region A, where you started, because those parts of space were joined together
But what if you don’t turn back after the first 100km? Instead you make a 90 º left turn, travel another 100km, turn left 90 º again, then travel another 100km – so you’re moving parallel to your first path as in the illustration below. You’ve followed three sides of a square, so now you must be 100km from the rendezvous, right? Again, this seems obvious, but is it? If you followed the same journey around New York’s famous grid of roads you could be confident of your location, because you know how the roads join up. But we’re talking about travelling through dark, empty nothingness. Can we rely on regions of space joining up in a well-behaved manner like Manhattan’s streets? As seasoned readers will know,
REGION C
REGION B
REGION D
REGION A
?
100km
REGION B
a moment ago during the outward journey. You confidently expect them still to be joined together. Given that, it’s not so strange to believe that space possesses some properties of it own. In fact, we rely on it having the property of connectivity – that each bit of space ‘remembers’ which other bits are its neighbours, so that when you retrace your path, you get back to where you started, because the space is still connected up in the same way.
Drop off point
Þ Whether you can return to the drop-off by moving in a square depends on how flat or curved the region of space is, represented by the question mark. When space is curved, you’ll end up elsewhere
THE BIG QUESTIONS DECEMBER 79
FLATLAND
We journey into Edwin Abbott’s ‘romance of many dimensions’ to find out how a 2D space can be curved after all
Fence
Tree
Fence
Þ The view exists in 3D, but we are only able to see it in 2D (left); in Flatland the view exists in 2D (middle), but its inhabitants only see in 1D (right) Flatland (named after the 1884 book Flatland by Edwin Abbott) is a universe of only two dimensions. Flatlanders can move around by turning left or right and moving forwards or backwards; there is no up or down. When a Flatlander looks out of his window, he has a 1D view of the 2D scene before him, just as our eyes see a 2D view of our 3D world. Let’s say a Flatlander travelled far into the unknown aboard a new super plane owned by Richard Flatson, the 2D tycoon (if you’re reading this box before the main text, trust me, this is hilarious). During his spacewalk, the Flatlander tried to follow a square path to meet Flatson back at the drop-off point. But he got hopelessly lost because the regions of Flatland don’t connect up in the simple way he expected. How sad it is to realise that he could have safely met with Flatson if he had recognised
the Universe is rarely well-behaved, but always entertaining. Here on Earth, where space is relatively simple, every time that I have followed a square path it has so far taken me back to my starting point. So I have come to expect it. But it doesn’t have to be that way. And, in many parts of the Universe, it isn’t. Don’t worry, the story of your inaugural spacewalk has a happy ending because, in our local neighbourhood of space, any 100km square joins up almost perfectly. But to navigate enormous distances, comparable to the size of the Universe, or even modest distances near a black hole, you cannot follow a square-grid-shaped map like the one pictured, because the regions of space don’t join up like that. Now we’re ready to define what is meant by ‘curved space’. If the regions of space meet each other in the straightforward way, so that an astronaut can follow a square or circular route and come back
Þ Because his space is curved, the spacewalking Flatlander reaches the drop-off point after three turns, even though he turned by 90º each time
to the beginning after turning through a total of 360 º, then we call that region of space ‘flat’. On the other hand, if the lengths along different parts of the path don’t agree with each other, then the space is called ‘curved’. In fact, it’s not just called curved, it’s curved in a very real sense. To see why, we must imagine what life would be like for a ‘Flatlander’ living in a 2D universe (see box, above).
Curved surfaces As early cartographers discovered, it’s impossible to map Earth’s surface in 2D using a simple square grid, because the surface of our planet is curved. Remember, curvature is the property where the parts of the surface don’t join together like a square grid. This definition makes sense even if, like Flatlanders, you cannot reach a vantage-point outside your curved space to get a good look at its shape. Flatlanders, who cannot rise above their curved
the drop-off point when he returned there after just three sides of the square! According to our definition of a curved space, Flatland is curved. In other words, its regions don’t meet up in a simple grid pattern, as you can see in the illustration on the left. You can reproduce the unlucky Flatlander’s journey for real, by travelling across the 2D surface of the Earth. Begin at the north pole and head in a straight line in any direction. Keep going until you reach the equator. Now turn left through exactly 90º and travel along the equator in a straight line for the same distance again. Make another 90º left turn and travel in a straight line, following what the Flatlander believed to be the third side of a square. Hey presto! You’re back at the pole. Perpendicular lines don’t form a square because the surface – ‘2D space’ – is curved.
universe to view its spherical shape, can still work out that their universe is curved by drawing a grid all over it and seeing how the shapes fit together. Another way that you can measure the curvature of a sphere (like Earth’s surface) without ever leaving it is to draw a big circle on it – for instance, the Arctic Circle – and measure its circumference. Next measure its diameter. You’re not allowed to leave the surface by drilling a tunnel through the Earth to measure a straight-line path; you have to trek across the Arctic, unravelling a tape measure, to find the diameter across the surface. Having obtained these two measurements, divide the Arctic Circle’s circumference by its diameter. Time to revisit a bit of high school maths: dividing the circumference of a circle by its diameter should always give you π (3.14159265358979 and a bit). But this isn’t the figure you end up with. The Arctic isn’t flat, it’s curved. It has > skyatnightmagazine.com 2012
82
HOW TO MAKE A
collimator
Focuser Primary mirror
With Mark Parrish
This simple alignment tool will help you to set up your Newtonian reflector quickly and accurately
Tools and materials
Save money by building your own collimator from household materials
CARDBOARD TUBE
You’ll need a short length (about 150mm) of stiff tube that’s about 30mm in diameter. A good source is the middle of a roll of tin foil. Wrap with tape to increase the diameter to 31.8mm, which is 1.25 inches exactly. FINISH
Matte black spray paint works well as a nonreflecting finish, and will help to prolong the collimator’s life. SUNDRIES
MARK PARRISH X 8, PAUL WHITFIELD
For the reflector, use small piece of bright or silvered card from a craft shop, or cut from some packaging. Use a plastic milk bottle top for the end cap and two dressmaking pins for the crosshairs. TOOLS
Fretsaw, coping saw or junior hacksaw, craft knife, sandpaper, ruler, pencil, scissors, glue and electrical tape.
skyatnightmagazine.com 2012
M
any astronomers own reflecting telescopes, and the most common design is the Newtonian. These mirror-based instruments provide much larger apertures for your money than refractors, which use lenses. Because of this, reflectors can capture more faint starlight, giving you brighter views of astronomical objects. A Newtonian’s two mirrors need to be perfectly aligned to give well-focused, high-contrast views of the night sky. Any rough handling or accidental impacts can knock the mirrors out of position, spoiling your view. Thankfully, the Newtonian design allows for small adjustments to be made to correct this. In this month’s project, we’re making a device to help you to perform these corrections accurately and get the best performance from your scope – a collimator.
Secondary mirror
Spider vane
Numerous commercial collimators and aids are available. Some are designed to help you visually align the secondary mirror with the focuser drawtube, others to help you align the primary mirror to reflect centrally along the main tube. Some variants help you to align the reflection from the secondary mirror, and many provide a mixture of functions. Our design is based on a combination tool called a Cheshire eyepiece, which helps tackle all three jobs. A collimator is basically a hollow tube with a small eyehole at one end. The length of the tube is calculated to suit the telescope, and you work it out by multiplying the internal diameter of the tube by the focal ratio of telescope. So, for example, if you have a piece of tube with an internal diameter of 25mm and an f/5.6 scope, then the length you’ll need is 140mm (25 x 5.6). This means that the outline of the secondary and primary mirrors should just fit inside the tube as you look down it, making visual alignment fairly straightforward. A cut-out section near the eyehole end holds a sloping, reflective piece of card. In daylight this KEY Collimator Secondary mirror Primary mirror Reflected collimator
POOR ALIGNMENT
GOOD ALIGNMENT
Þ The collimator view shows the different elements that need to be aligned to get the best from a telescope
HOW TO DECEMBER 83
shows up nicely when reflected back by the mirrors and at night you can illuminate it with a red torch. Crosshairs at the far end of the tube help with the fine adjustment of the primary mirror, which ideally should have a central ring or dot sticker on it. Most telescopes come with instructions that explain how to adjust the mirrors. This typically involves turning three screws behind each mirror, either by hand, with a small Allen key or with a screwdriver. Sometimes there are locking nuts or separate screws that need to be loosened before you can adjust the main screws, and retightened after adjustment to maintain the correct position.
How to use it Using our collimator is quite straightforward. First, position it carefully in the focuser. When you look through the small eyehole you should be able to see the outline of the secondary mirror. If needed, physically adjust the secondary so it appears centrally placed in the collimator tube – usually this is set up quite accurately in the factory. Next, adjust the screws on the secondary mirror so that the reflected outline of the primary mirror also appears central. If your primary has a central dot or ring, then you can use your crosshairs to get the best alignment, otherwise, you can align it with the edge of the tube. Finally, make small adjustments to the primary mirror so that the reflection of your collimator appears central as well. You will probably have to move between ends of the scope to make these adjustments, so make a mental note of which screw you have moved each time or you might get in a muddle. When all the reflections and outlines appear centralised in the collimator, you know that all three elements (focuser, secondary mirror and primary mirror) are physically in line and also optically aligned. Make sure you have tightened up any locking nuts or screws; you may need to make some further small adjustments afterwards as this can move the mirrors a little. Once your telescope is well collimated you should only ever need to make small adjustments, usually only to the primary mirror. It’s worth spending a few minutes before every observing or imaging session to make sure you are getting the best performance from your equipment. S
STEP-BY-STEP GUIDE
STEP 1 Mark out a length of tubing to suit your scope: this should be equal to your scope’s focal ratio multiplied by the tube’s internal diameter in millimetres. Use a simple wooden jig to make 45° cuts to form the reflector opening close to the mark, then cut to length.
STEP 2 Hold a scrap of sandpaper on the edge of a table and rub the tube back and forth to sand the opening and ends until they’re nice and straight. If you’re using the tube from a roll of tin foil, lightly sand the outside as well to remove any sticky residue.
STEP 3 Use the template on our coverdisc to carefully mark out a reflector to suit your tube. If you are short of reflective card, practise the shape with scrap card first, to make sure it fits nicely. Carefully cut out with scissors and use a craft knife to create a hole.
STEP 4 To mark out the crosshairs, wrap a strip of paper round the tube. Cut it so it is exactly the length of the circumference – there should be no overlap. Fold the paper in half twice and unfold to mark four quarters. Rewrap and mark the tube at the quarter positions.
STEP 5 Once you have pushed the pins through for the crosshairs, use a nail or sharp point to make a hole in the centre of the bottle cap. Before gluing the reflector and cap in place, give the tube a coat of matte black paint – spray paint will do the job quickly.
STEP 6 You will probably need to increase the diameter of the cardboard tube to give it a sliding fit in the focuser drawtube. We wrapped two strips of thin card followed by a few turns of blue electrical tape around our tube, to beef up the diameter to 1.25 inches.
skyatnightmagazine.com 2012
EQUIPMENT Q&A DECEMBER 85
SCOPE
doctor
Our resident equipment specialist Steve Richards cures your optical ailments
What numbers should I enter into my Go-To mount’s handset when setting up? EDWARD McENTEE
PAUL WHITFIELD, STEVE MARSH
For a Go-To mount to accurately find celestial objects, it needs to build up a ‘map’ of where they should be in the sky relative to your location. However, this map must also be synchronised with the date and time that you are observing so the built-in computer in the handset can determine exactly where to point the telescope for that particular time of the year.
The basic information you have to enter for the Go-To handset to be able to do this is your location, time zone, date and local time. You also need to tell it whether your local time is currently affected by daylight saving time (British Summer Time), though of course that’s not the case in December! The Meade Autostar and Celestron NexStar Go-To systems include a wide choice of named geographical locations, so you may be able to simply choose the nearest city to where you are. The Vixen Star Book and Sky-Watcher handsets require you to enter the longitude and latitude of your site; this information can be found on an Ordnance Survey map, using a GPS receiver or online at sites such as www.getlatlon.com or www.itouchmap.com. Many handsets have an optional GPS module that will automatically enter the location, date and time when you switch the telescope on. If you have to do this manually, check the required date format carefully as many systems use the US style of mm/dd/yyyy rather than the UK’s dd/mm/yyyy.
< Most Go-To mounts need location details to accurately move a scope, but how much you have to enter yourself varies by model
STEVE RICHARDS Our Scope Doctor and all-round gear guru is a keen amateur astronomer and astrophotographer. He loves nothing more than tinkering with telescopes and accessories.
STEVE’S TOP TIP
What’s the best way to remove vignetting? Vignetted images display well-illuminated centres but light levels that fall off towards the edges of the field of view, as can be seen in this shot of the Moon. This can be caused path, for by a physical obstruction in the light with a large tube s focu example, using a 1.25-inch ration file calib a ng racti subt sensor. Applying and g editing usin es imag your of each to called a ‘flat’ is an image flat A software is a very successful solution. same focus the and n tatio taken at exactly the same orien cope teles the with but e, imag position as the original surface. lit ly even se, diffu ly plete com a at or lens pointing
If I fit heavy equipment to the viewing end of my Celestron NexStar102SLT, I need to balance it at the other end: the gearing in the fork arm doesn’t keep the scope steady. What can I do? ANDRZEJ CHIRKOWSKI
The Celestron NexStar 102SLT is a 4-inch refractor with a 660mm focal length on a computerised Go-To altaz mount. Balancing the scope is important to avoid overtaxing the drive system. Used with the 25mm and 9mm eyepieces supplied, the drive motors and gear train can comfortably handle the telescope. However, loading the telescope with heavy photographic equipment or a large 2-inch eyepiece and diagonal could unsettle the mount and place undue strain on the gears leading to early wear, inaccurate Go-To manoeuvres and poor tracking. Although Celestron produce a balance bar system, it is designed for use with their Schmidt-Cassegrains and would not be suitable for your refractor without extensive modification. You’ll need to take a homebrew approach: you could attach suitable weights, made from metal strips, using hook-and-loop fastener pads fixed to the top of the dew shield.
Email your queries to
[email protected] skyatnightmagazine.com 2012
WHAT’S ON DECEMBER 87 EAST ANGLIA
OBSERVING EVENING St Neots AA, Little Paxton Nature Reserve Visitor Centre; 3 December at 7.30pm; free for members, visitors welcome; email
[email protected]; www.snaa.co.uk
AN EVENING WITH THE STARS Royal Observatory, Greenwich, 12, 14, 15 and 19 December, 5.30pm and 6.50pm
For a night of assorted astronomical treats head down to the Royal Observatory, Greenwich for an evening of astronomy. After a tailored planetarium show to highlight what’s in the night sky on the evening you visit, you’ll have the opportunity to look through the observatory’s 28-inch Victorian telescope. Later, you’ll get a chance to spend some time on the prime meridian, sipping hot drinks and taking in the views with a team of experienced astronomers on hand to answer your questions. Sessions run
TALK: THE FUTURE OF SPACE TRAVEL Dave Cook; Norwich AS, Seething Observatory, Toad Lane, Thwaite St Mary; 7 and 8 December at 7.30pm; members £2, visitors £3, children £1.50; email
[email protected]; www.norwich.astronomicalsociety.org.uk
The scope is kept in the distinctive ‘Onion Dome’
from 5.30pm-7.30pm and 6.50pm-8.50pm. Tickets cost £16 per adult and £14 for children and concessions. www.rmg.co.uk/visit/events/evening-withstars-dec-2012
TALK: THE RISE AND FALL OF PLUTO Martin Lunn; Derby and District AS; Friends’ Meeting House, St Helen’s Street, Derby; 7 December at 7.30pm; members £1, visitors £3; email
[email protected]; www.derbyastronomy.org
TALK: IMAGES OF THE EARTH Paul Money; Mexborough and Swinton AS, Swinton Working Men’s Club, Station Street, Swinton; 20 December at 7.45pm; free for members, small charge for visitors; call 01709 584217; http://msas.org.uk
TALK: EDMOND HALLEY – ENGLAND’S SECOND GREATEST ASTRONOMER Prof David Hughes; Sheffield AS, Mayfield Environmental Centre, David Lane, Fulwood; 10 December at 7.45pm; free for members, visitors £3; email
[email protected]; www.sheffieldastro.org.uk
MIDLANDS
TALK: REVIEW OF THE SPACE YEAR Dr Michael Martin-Smith; Hull and East Riding AS, Wilberforce Building, University of Hull, Cottingham Road, Hull; 10 December at 7.30pm; free for members, visitors £1.50; email
[email protected]; www.heras.org.uk TALK: CHEMICAL ANALYSIS IN SPACE Anthony Bristow; West Didsbury AS, William Hulme Grammar School, Manchester; 10 December at 7pm; free for members, visitors welcome; email
[email protected]; www.wdas2.com TALK: THE CHEMISTRY OF THE INTERSTELLAR MEDIUM Dr Paul Ruffle; Hebden Bridge AS, Hope Baptist Church, Hebden Bridge; 12 December at 7.30pm; free for members, visitors £3; email
[email protected]; www.hbas.org.uk
SPACE NOW EXHIBITION National Space Centre, Exploration Drive, Leicester; throughout December (not Mondays); adults £13, concessions £11; call 0116 261 0261; www.spacecentre.co.uk PLANETARIUM SHOWS Thinktank Planetarium, Millennium Point, Birmingham; throughout December; adults £10.95, concessions £9.10 (includes museum ticket); call 0121 202 2222; www.thinktank.ac TALK: CCD IMAGING Nik Szymanek; Rugby and District AS, Church Lawford Village Hall, School Street, Church Lawford; 1 December at 7.30pm; email rugby-astro@ hotmail.co.uk; www.rugbyastro.org.uk TALK: ULTRA HIGH-ENERGY COSMIC RAYS Dr Matthew Malek; Stratford-Upon-Avon AS, Alderminster Village Hall, New Road, Alderminster; 4 December at 7.30pm; free for members, visitors welcome; email
[email protected]; www.astro.org.uk TELESCOPE TOPICS Northants AA, The Lamb, Orlingbury Road, Little Harrowden; 4 December at 7.45pm; free for members, visitors welcome; email janegillsmills@ yahoo.co.uk; www.naastronomy.com
TALK: ALAN CHAPMAN’S CHRISTMAS LECTURE Alan Chapman; Salford AS, Room 115, Maxwell Building, University of Salford, The Crescent, Salford; 12 December at 7.30pm; free for members, visitors welcome; email
[email protected]; www.salfordastro.org.uk
MEMBERS’ EVENING Coventry and Warwickshire AS, Earlsdon Methodist Church, Earlsdon Avenue South, Coventry; 14 December at 7.15pm; free for members, visitors welcome; email
[email protected]; www.covastro.org.uk
MEMBERS’ OBSERVATIONS AND RESEARCH PRESENTATIONS Liverpool AS, The Quaker Meeting House, School Lane, Liverpool; 14 December at 7pm; free for members, visitors welcome; email ggastro@ liverpool.ac.uk; www.liverpoolas.org
TALK: BLACK HOLES Paul Shepherd; Heart of England AS, Old BT Telephone Exchange, Furnace End, Shustoke; 20 December at 8.30pm; free for members, visitors welcome; email
[email protected]; www.hoeas.co.uk
TALK: IT’S THE END OF THE WORLD AS WE KNOW IT Andrew Briggs; Breckland AS, Great Ellingham Village Hall; 14 December at 7.30pm; free for members, visitors welcome; email newsletter@ brecklandastro.org.uk; www.brecklandastro.org.uk
WALES
PLANETARIUM SHOWS Techniquest Planetarium, Cardiff; most weekends in December, check website for prices and dates; call 029 2047 5475; www.techniquest.org TALK: ASTRONOMY WITHOUT A TELESCOPE Martin Chick; Swansea AS, Swansea University; 6 December at 7pm; free for members, visitors welcome; email
[email protected]; www.swanastro.org.uk TALK: SETTING SAIL FOR THE STARS Andrew Lound; Swansea AS, Swansea University; 8 December at 7pm; free for members, visitors welcome; email
[email protected]; www.swanastro.org.uk TALK: ASTRONOMY AND THE TITANIC Andy Lound; Cardiff AS, Cardiff University Dept of Physics and Astronomy, The Parade, Newport Rd; 13 December at 7.30pm; free for members, visitors welcome; email
[email protected]; www.cardiffastronomical-society.co.uk TALK: SMOKING SUPERNOVAE FROM THE HERSCHEL SPACE OBSERVATORY Dr Haley Gomez; Bridgend AS, Pyle Church Hall, Pyle, Bridgend; 14 December at 7.30pm; email
[email protected]; www.bridgendastronomicalsociety.co.uk
SOUTH
EXPLORING SPACE Science Museum, South Kensington, London; throughout December; free for all; call 0870 870 4868; www.sciencemuseum.org.uk PLANETARIUM SHOWS South Downs Planetarium, Chichester; throughout December; adults £6, under-16s £4, booking advised; call 01243 774400; www.southdowns.org.uk ASTRONOMY PHOTOGRAPHER OF THE YEAR 2012 EXHIBITION Royal Observatory, Greenwich; until February 2013; free; call 020 8312 6608; www.nmm.ac.uk TALK: THE STAR OF BETHLEHEM, AN ASTRONOMER’S VIEW Prof David W Hughes; Guildford AS, University of Surrey, Guildford; 6 December at 7.30pm; free for members, visitors £3; email secretary@guildfordas. org; www.guildfordas.org
TURN OVER FOR MORE EVENTS
skyatnightmagazine.com 2012
88 WHAT’S ON DECEMBER TALK: SIR ISAAC NEWTON Prof Robert Iliffe; East Sussex AS, St Mary’s School, Wrestwood Road, Bexhill-on-Sea; 6 December at 6pm; visitors welcome; email simon.sallen@ gmail.com; www.esas.org.uk PUBLIC STARGAZING South East Kent AS, The Langton Star Centre, Simon Langton Grammar School, Langton Lane, Nackington Road, Canterbury; 7 December at 7.30pm; email
[email protected]; www.sekas.co.uk ASTROMEET Milton Keynes AS, Rectory Cottages, Bletchley; 7 December at 8pm; free for members, visitors welcome; email
[email protected]; www.mkas.org.uk
17 December at 7.30pm; free for members, visitors £4; email
[email protected]; www.worthing-astronomical-society.com TALK: MAKING AND USING A NEWTONIAN Mark Radice; Solent AA, Eastpoint Centre, Bursledon Road, Thornhill, Southampton; 18 December at 7.30pm; email
[email protected]; www.delscope.demon.co.uk/society USER GROUP: HOW TO USE YOUR TELESCOPE Ewell AS, Nonsuch High School for Girls, Ewell Road, Cheam; 29 December at 7.45pm; email
[email protected]; www.ewellastronomicalsociety.com
SOUTH WEST
TALK: DEEP-SKY OBJECTS Owen Brazell; Reading AS, St Peter’s Church Hall, Earley; 8 December at 7pm; free for members; email
[email protected]; www.readingastro.org.uk
THE WINTER NIGHT SKY At-Bristol Planetarium, Millennium Square, Bristol; throughout December, 11am-2pm; check website for prices; call 0845 345 1235; www.at-bristol.org.uk
TALK: CATACLYSMIC VARIABLES Prof Christian Knigge; Abingdon AS, All Saints Methodist Church, Dorchester Crescent, Abingdon; 10 December at 8pm; free for members, visitors welcome (call in advance); email chris.c.holt@ ntlworld.com; www.abingdonastro.org.uk
PLANETARIUM SHOWS INTECH Science Centre and Planetarium, Winchester; throughout December; admission plus £2.20 or £4.75 standalone (weekends only); call 01962 863791; www.intech-uk.com
TALK: THE ATMOSPHERES OF JUPITER AND SATURN Dr Leigh Fletcher; West of London AS, St John’s Ambulance Hall, North Harrow; 10 December at 8pm; free for members, visitors welcome; email
[email protected]; www.wolas.org.uk TALK: THE SKY’S DARK LABYRINTH Dr Stuart Clarke; Hertford AG, Hatfield Cricket Club, Ascots Lane, Welwyn Garden City; 12 December at 8pm; free for members, visitors welcome; email
[email protected]; www.hertsastro.org.uk TALK: THE T200 TELESCOPE FIRST LIGHT Paul Treadaway; Wadhurst AS, Methodist Church, Lower High Street, Wadhurst; 12 December at 7.30pm; free for members, visitors £2; email
[email protected]; www.wadhurst.info/was STARGAZING: THE END OF THE WORLD? Baker Street Irregular Astronomers, The Hub, Regent’s Park, London; 12 December at 6.30pm (confirm via website); email ralph@bakerstreetastro. org.uk; www.bakerstreetastro.org.uk OBSERVING EVENING > See ‘An evening with the stars’, page 87; 12, 14, 15 and 19 December at 5.30pm and 6.50pm TALK: PROJECT ORION – SATURN BY 1970 Andy Coupland; Basingstoke AS, Cliddesden Primary School; 13 December at 7pm; free for members, visitors welcome; email john.stapleton@ tesco.net; www.basingstokeas.org.uk
MEMBERS’ VIDEOS AND DIGITAL IMAGES Wessex AS, Allendale Centre, Wimborne; 4 December at 7.30pm; free for members, visitors welcome; email
[email protected]; www.wessex-astro.org.uk TALK: THE MOON Tony Deyes; Torbay AS, Torquay Boys’ Grammar School, Shiphay Manor Drive; 6 December at 7.30pm; free for members, visitors £2; email
[email protected]; www.halien.net/TAS TALK: THE NEW KEPLERIAN REVOLUTION > See ‘Extraordinary exoplanets’, page 86; 12 December at 6.30pm PUBLIC OBSERVING EVENT Wessex AS, Durlston Country Park, Swanage; 14 December at 7pm; visitors welcome; email
[email protected]; www.wessex-astro.org.uk
TALK: IMAGING THE MOON, SUN AND PLANETS Bud Budzynski and Ron Westmaas; Crewkerne and District AS, St Bartholomew’s Church Hall; 19 December at 7.30pm; free for members, visitors welcome; email
[email protected]; www.cadas.net TALK: SOUTHERN SKIES Alan Dowdell; Andover AS, Grately Village Hall, Andover; 20 December at 7.45pm; free for members, visitors welcome; email webmaster@ andoverastronomy.org.uk; www.andoverastronomy.org.uk
TV and radio The Sky at Night – see page 86 Scanning the Skies: The Discovery Channel Telescope Discovery HD, 9 December, 8pm Astronomers explain how the 4.3m Discovery Channel Telescope will bring images of our Solar System and beyond directly into homes. Mars landing 2012 Discovery Science, 10 December, 8pm With exclusive access to mission personnel, this documentary looks at the science and technology that safely delivered NASA’s Curiosity rover to the Red Planet. Follow the star BBC Radio 2, 24 December, 7pm Hardeep Singh Kohli and Dr Marek Kukula enlist the help of astronomers, historians and theologians to unravel the mystery of the Star of Bethlehem and the most famous stargazers in history, the Three Wise Men. They recreate the cosmos as it would have been 2,000 years ago using planetarium projections, which listeners can follow on www.bbc.co.uk/radio2/followthestar Check www.radiotimes.com as times may vary
CHRISTMAS SURVIVAL GUIDE: THE ANSWERS Haven’t tested your knowledge yet? Check out our Christmas Survival Guide on page 44. Astro quiz of the year [1] Steven F Udvar-Hazy Center of the Smithsonian National Air and Space Museum [2] Gale [3] the rocket engines from Apollo 11’s Saturn V [4] M67 [5] Rocky planets [6] Queensland and the Northern Territory [7] The Whirlpool Galaxy, M51 [8] Pioneer 10 [9] Dragon [10] Albireo (Beta Cygni) [11] Prof Stephen Hawking [12] Dulverton [13] Ceres [14] Gemini 8 [15] Round Picture puzzle [1] Mimas, Saturn [2] Sojourner [3] George Biddell Airy [4] Western Australia; it’s Wolfe Creek Crater [5] Aquarius [6] Keck I and Keck II
OPEN EVENING – GEMINID METEORS The Observatory Science Centre, Herstmonceux, East Sussex; 14 December at 6.30pm; adults £8.60, concessions available; email info@ the-observatory.org or call 01323 832731; www.the-observatory.org
ASTRONOMY EVENTS EMAIL
TALK: ASTRONOMY MEETS ARCHAEOLOGY Bob Turner; Worthing AS, Emmanuel United Reformed Church, Heene Road, Worthing;
[email protected]
To ensure that your talks, observing evenings and star parties are publicised in Sky at Night Magazine, please send the details to the following email address at least two months in advance of publication:
For more society events, visit http://forum.skyatnightmagazine.com or http://fedastro.org.uk skyatnightmagazine.com 2012
REVIEWS DECEMBER 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
We examine the uncommon RiccardiHonders optical design of Officina Stellare’s 8-inch astrograph
This month’s reviews
PAUL WHITFIELD
First light
90
Officina Stellare RH-200 8-inch astrograph
94
Vixen Sphinx Pro equatorial Go-To mount
98
Orion StarShoot G3 monochrome CCD camera
Books
Gear
102
104
We rate four of the latest astronomy titles
Including this 2-inch to 1.25-inch adpator
Find out more about how we review equipment at www.skyatnightmagazine.com/scoring-categories skyatnightmagazine.com 2012
90
FIRST light Officina Stellare RH-200
8-inch astrograph
SKY SAYS… Our test images of bright star Vega in Lyra showed good star shapes right into the edges of the field of view
We examine whether the imaging prowess offered by an unusual optical design justifies a steep price tag WORDS: STEVE RICHARDS
VITAL STATS • Price £5,799 • Optics RiccardiHonders catadioptric • Aperture 200mm (8 inches) • Focal Length 600mm • Focal ratio f/3 • Focuser Micro adjustment Crayford • Finder not supplied • Extras Padded hard case • Weight 10.1kg • Supplier The Widescreen Centre • www.widescreencentre.co.uk • Tel 020 7935 2580
I
f excellent engineering and Italian design determined whether a telescope was suitable for astrophotography, then Officina Stellare’s Veloce RH-200 would be a world beater. With its black, high-gloss alloy tube, red anodised hardware and carbon fibre dew shield, the RH-200 is a stunningly beautiful piece of equipment. On looks alone you’d be forgiven for taking this astrograph for a Schmidt- or Maksutov-Cassegrain. Certainly the reflective central obstruction is reminiscent of the latter. However, appearances can be deceptive; the first clue that this is a different beast altogether is its focal ratio of just f/3. SchmidtCassegrains typically have focal ratios around f/10, Maksutov-Cassegrains around f/15. The tube itself is an extremely short 22cm – it’s only the presence of the dew shield that gives the scope its Cassegrain-like shape. The dew shield has a bevelled edge that acts as a baffle, leaving an 8-inch clear aperture. It’s also retractable, though you can only do this after unmounting the scope as part of the locking mechanism is incorporated into the fixing of the Vixen-style dovetail bar. The simple ‘shower cap’ style dust cover was a disappointment here – it really seemed out of keeping with the rest of the telescope.
There’s a clamp on top of the optical tube for attaching accessories such as finderscopes and autoguiders, but it’s an unsual design, taking the form of a small, Vixen-compatible dovetail clamp rather than the typical Synta-style finderscope clamp. At the time of review, no accessory was available that would let us attach our own Altair Astro 60mm guidescope, but we were able to easily make one by cutting off a small section from a spare Vixen-compatible dovetail bar, which worked very well. Officina Stellare is planning to introduce a similar solution of their own in future.
Fine focus We tested the imaging capabilities of the RH-200 on an Avalon M-UNO mount. There needs to be 115mm between the camera sensor and the rear of the scope for the two-element field-flattener to deliver the best results, so Officina Stellare supply adaptors for several types of CCD camera. Using the one for use with >
ALL PHOTOS: PAUL WHITFIELD
RICCARDI-HONDERS OPTICAL DESIGN Refractors tend to suffer from spherical aberration, causing elongated stars to appear at the edge of the field of view, and chromatic aberration, which results in colour fringing. Reflectors on the other hand, are likely to suffer from coma, resulting in stars at the edge of the field of view appearing comet-shaped. This is where the RH-200’s RiccardiHonders optical design comes in. It uses a combination of lenses and mirrors to produce colour-corrected images and a flat field of view with good star shapes, despite the very fast focal ratio of just f/3.
skyatnightmagazine.com 2012
The crucial element of the optical design used here is the primary negative meniscus lens-mirror, which is called a Mangin mirror after its inventor, Alphonse Mangin. The Mangin mirror has a reflective coating on its rear surface; light that passes through the lens is reflected off this and back through the glass a second time. The effect is that the under-corrected spherical aberration of the mirror is offset by the overcorrected spherical aberration of the negative lens, giving a crisp final view.
Þ The optics are uncommon, but undoubtedly effective
FIRST LIGHT DECEMBER 91
DEW SHIELD The carbon fibre dew shield does an excellent job of protecting the front correction plate from dewing up and cutting out extraneous light. It can also be retracted, but only after the scope has been removed from its mount because part of the excellent attachment mechanism has been incorporated in the dovetail fixing.
MICROFOCUSER There needs to be a 115mm gap between the back plate and the camera sensor to ensure the two-element flattener at the rear of the RH-200 delivers an optimal flat field. Officina Stellare pre-focuses the telescope and supplies specific adaptors for several CCD cameras. Additional small adjustments can be made using the focuser’s thumbwheel.
CAMERA TILT ADJUSTMENT In fast focal ratio telescopes the focus sweet spot is small, so it’s vital that the sensor is perfectly parallel to the image plane – otherwise, the stars on one side of the field of view could be out of focus. A set of four push-pull bolts (one annotated) and a spring-loaded plate allow you to make fine adjustments to ensure accurate alignment.
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92 FIRST LIGHT DECEMBER
FIRST light PIGGYBACK MOUNTING Guiding is essential if you want to take long exposures of deep-sky objects, and this is often accomplished using a second telescope and guide camera. Mounting the guide telescope can be challenging, but the RH-200 has a slim Vixen compatible saddle clamp installed on the optical tube’s top for this purpose.
COLLIMATION ADJUSTMENT Only the primary mirror can be moved for collimation. This is performed using the disc of a defocused star with the central obstruction clearly visible. Adjusting the three spring-loaded primary mirror adjustment bolts using an Allen key to centre the view of the obstruction is very straightforward, although the scope arrived in excellent collimation.
< Our test image of the Dumbell Nebula, comprised of 32 60-second exposures
SKY SAYS… Now add these: 1. Avalon M-UNO equatorial mount
PAUL WHITFIELD, STEVE RICHARDS
2. Geoptik hardwood tripod 3. Atik 11000 monochrome or colour CCD camera
skyatnightmagazine.com 2012
> our Starlight Xpress M25C one-shot colour CCD, we were amazed to discover that the telescope was in perfect focus straight out of the box. The astrograph’s focuser is a 3-inch Crayford design with microfine adjustment calibrated in microns. One complete turn of the thumbwheel is equal to 800μm of movement. A gold-coloured locking collar prevents any unwanted movement once focus is achieved, while the careful choice of materials removes any need to alter the focus due to temperature changes. We didn’t have to refocus throughout the 15-day review period. For our first test we took a series of unguided, one-minute exposures of the Dumbbell Nebula in Vulpecula. We wanted to see how much data a fast scope like this could collect with a relatively short exposure and we were impressed with the result: well-formed stars were visible right to the edges of the field of view of our APS C sized sensor,
which is the same size as the sensor in a standard DSLR camera. Our test images of bright star Vega in Lyra proved equally impressive, with really good star shapes right into the edges of the field of view, a testament to how well the optical design controls field flatness. We really enjoyed using this telescope and would warmly recommend it to any advanced astro imager interested in taking excellent wide-field images. S
VERDICT BUILD AND DESIGN EASE OF USE FEATURES IMAGING QUALITY OPTICS OVERALL
★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★★
Inspiring young minds! AQUILA Children’s Magazine is ideal for boys and girls who want to know the whys and wherefores of everything. “How does a lava lamp work?” “Was there really a curse on Tutankhamun’s tomb?” The magazine starts its young readers on the right track and feeds their interest with factual articles, puzzles and fun-activities that are designed to ignite children’s enthusiasm and creativity. Every monthly issue of AQUILA has a new topic. There’s no celebrity gossip or advertorial; instead, children can deepen their interest and understanding of the world around them. Says Editor Jackie Berry, “We never talk down to our readers, and they love to be part of a magazine that takes them seriously.”
Great gift for 8-12 ye ar olds
Research suggests that one in five primary-aged children finds school work too simple, so it is reassuring to know that AQUILA Magazine, which is recommended by educational specialists, will provide challenges for our brightest children. You will not find AQUILA at the newsagents; it is only available by subscription.
“Thank you for looking after my son’s brain!” www.aquila.co.uk • 01323 431313
NIPON SCOPE & OPTICS
A wide range of Nipon telescopes, spotting scopes, binoculars, monocular, microscopes, and optical accessories available from Nipon Scope & Optics online store and from our UK warehouse. Digital eyepiece/camera and various camera adaptors for telescopes are also among our featured products. We offer spectacular savings with probably the best UK prices and express courier delivery for almost all Nipon optical instruments and accessories.
www.nipon-scope.com Tel: 0844 318 7890 E-mail:
[email protected]
94
FIRST light
Vixen Sphinx Pro
SKY SAYS… Go-To accuracy was very good, with objects appearing comfortably in the middle 25 per cent of the field of view
equatorial Go-To mount A series of thoughtful and innovative tweaks make this mount worthy of closer inspection WORDS: STEVE RICHARDS
VITAL STATS • Price £3,499 • Load capacity 16kg • Hand controller Star Book Ten • Database 272,242 objects • Flash upgradeable Yes, via RJ45 network connection • Autoguider port Standard ST-4, via Star Book Ten controller • Counterweights Two: 3.7kg and 1.9kg • Tripod Not supplied • Weight 11kg, excluding counterweights • Supplier Opticron • www.vixenoptics.co.uk • Tel 01582 726522
V
ixen has an excellent reputation for producing well-engineered products and the Vixen Sphinx Pro mount is no exception. It simply exudes quality. We were impressed with the fit and finish of all of the components, with nicely thought out detailing everywhere you look. The mount head arrived in a fully fitted and substantial flight case, and attaching it to the SXG Hal-130 aluminium tripod (£179; sold separately) proved a simple task for one person. Much of the casing and many of the components have been placed on the counterweight side of the right ascension axis. This simple idea adds a notable amount of counterbalance, which reduces the overall weight that you need to carry when you take the scope out observing. Two counterweights are included, one of 3.7kg and a smaller one of 1.9kg. Both fit onto a retractable, 20mm-diameter counterbalance shaft. The declination axis carries a Vixen-style dovetail mounting block with a single clamping bolt and a small safety retaining bolt to ensure that the dovetail bar doesn’t slip. We used our own Vixen-to-Losmandy adaptor plate to mount our William Optics FLT98 refractor.
Vixen’s excellent polarscope was already installed on the mount, and was quick and intuitive to use. Azimuth adjustment is achieved by moving two opposing bolts against a fixed post on the tripod’s top plate in the conventional manner, but altitude adjustment was rather different. The mount is supplied with its latitude set to the middle of three ranges, each covering approximately 15º. For the UK, it is necessary to adjust the range to the ‘high’ position by removing an Allen bolt and rocking the mount upwards to expose a new bolt location. This was a simple task using the supplied Allen key. For fine adjustment, you need to release a clutch on the side of the mount and turn a single pitchthreaded hand bolt. This is connected to a carrier that moves the mount up and down in latitude. The system was very easy to use and showed a marked improvement on the usual opposing bolts method.
Star controller We rather liked using the Star Book Ten hand controller as it includes a fully featured planetarium application and telescope control – it made finding celestial objects an absolute breeze. You simply use >
ALL PHOTOS: PAUL WHITFIELD
POWER IN THE PALM OF YOUR HAND We immediately felt at home with the innovative Star Book Ten (‘heaven’ in Japanese) controller. Its TFT LCD screen is a generous 5 inches, and its resolution of 800x480 pixels, 65,000 colours and adjustable backlighting made the system easy to use. The night-vision mode is also welcome – it converts the screen view to red to help maintain your dark-adapted vision. Information is available for many of the objects in the extensive database, including thumbnail images, and a built-in Moon map allows you to home in on some lunar features,
skyatnightmagazine.com 2012
which will certainly appeal to less experienced observers. Navigating the numerous menus and dialogue boxes using the four direction keys, two zoom keys and the numeric keypad is very intuitive, and all of these buttons had a good feel to them despite our cold hands. The controller’s ‘Chart Mode’ gives you access to many of the features that you would expect to find in a typical planetarium application, while swapping to ‘Scope Mode’ makes the telescope follow your selections from object to object.
Þ Star Book Ten’s tactile keys proved great for cold hands
FIRST LIGHT DECEMBER 95
MOUNT BLOCK A Vixen-style mounting block sits on the declination axis; a single clamping bolt and a safety retaining bolt secure a telescope’s dovetail bar.
DATABASE POLARSCOPE Polar alignment couldn’t be much simpler. Adjust the hour circle’s built-in spirit level until it’s horizontal, rotate the illuminated polarscope until the current time and date are aligned with one another, then adjust the altitude and azimuth bolts until Polaris is aligned in the date-corrected reticule.
With over 272,000 objects stored, the Star Book Ten controller offers good access to a range of celestial delights selected from the Solar System and the Smithsonian Astrophysical Observatory, NGC, IC and Messier catalogues. There is also an excellent lunar exploration database.
ALTITUDE ADJUSTMENT Adjusting the altitude on many equatorial mounts can be a frustrating process as you have to overcome both gravity and tension while aligning Polaris, which you often have to do at an awkward viewing angle. However, the elegant clutch and carrier system used in the Sphinx Pro’s altitude mechanism makes this important adjustment very smooth indeed.
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96 FIRST LIGHT DECEMBER
FIRST light
STANDALONE CONSOLE The Star Book Ten hand controller can be removed from the mount and programmed on its own, so long as you connect it to a 12V supply. You can also set up orbital elements for comets and artificial satellites easily, using your PC’s web browser and a standard network cable.
CAREFUL BALANCE SKY SAYS… Now add these: 1. Vixen SXG HAL-130 aluminium tripod 2. Vixen AX103S ED refractor 3. Vixen SXG half pillar > the planetarium application to zoom in on the area of sky that you are interested in, centre your chosen object in the crosshairs and then command the mount to slew to the object. Go-To accuracy was very good, with objects appearing comfortably in the middle 25 per cent of the field of view and remaining there for well over half an hour. We particularly appreciated the fact that the mount has a small battery that keeps the date and time running when the mount is turned off, so these parameters don’t need to be entered at the start of each observing session. Unguided 5-minute exposures through our William Optics FLT98 produced star trails as you would expect, but connecting our Altair Astro miniguider and Starlight Xpress SXV autoguider to the ST-4 port on the Star Book Ten provided an instant solution using the default settings. We were impressed with how easy it was to set up the autoguiding; the flashing of the relevant direction arrows on the Star Book Ten in response to guiding corrections was a nice touch. Easy to assemble, quick to align, intuitive to use and supplied with a very comprehensive manual, there’s much to like about this mount whether you’re a beginner or a seasoned astronomer. Its standalone credentials – the fact that you don’t need a computer to access its good planetarium application – make it particularly appealing to visual astronomers. With its 16kg load capacity, accurate polar alignment and built-in autoguiding, it makes an excellent imaging platform when used with a guidescope and camera. S
ALL PHOTOS: PAUL WHITFIELD
VERDICT ASSEMBLY BUILD AND DESIGN EASE OF USE GO-TO ACCURACY STABILITY OVERALL skyatnightmagazine.com 2012
★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★★
Equatorial mounts need counterweights to offset the weight of an attached telescope, but they can create unwanted inertia on the right ascension axis. The clever design of the Sphinx Pro incorporates many heavier components on the counterweight side of the right ascension axis, which means you can get away with using lighter weights.
y m o n o r t s A
Friendly Advice and After-Sales Service. Buy online with confidence or visit our well stocked showrooms. Birstall, West Yorks WF17 9ES 01924 477719
Gransden, Beds & Cambs SG19 3PF 01767 677025
www.green-witch.com
98
FIRST light
Orion StarShoot G3
monochrome CCD camera An entry-level model with a smattering of advanced features – but can they make this CCD stand out from the crowd? WORDS: PETE LAWRENCE
VITAL STATS • Price £499 • Dimensions 75mm long, 85mm in diameter • Weight 340g • Sensor Sony ICX419ALL, 752x582 pixels (437,664 total) • System requirements Pentium III processor or equivalent, Windows XP/Vista/7, 512MB RAM, USB 2.0 port • Supplier The Widescreen Centre • www.widescreencentre.co.uk • Tel 020 7935 2580
T
he Orion StarShoot G3 is a cooled CCD camera designed for deep-sky imaging. Two variants are available, one for monochrome imaging and the other for one-shot colour imaging. For the purposes of this review, we’re looking at the monochrome version, which produces greyscale images. This camera is pitched as an entry-level device with advanced features normally found on higher end and more expensive models, such as thermoelectric cooling. We were particularly interested in how the camera works with basic imaging setups, both as a primary imaging
camera and – seeing as the G3 has a built-in ST-4 port – an autoguiding camera. Externally, as is the way with many modern CCD cameras, there’s not much to see apart from the camera body, front aperture and rear connection ports. The front aperture is T-threaded and pre-fitted with a 1.25-inch barrel adaptor as standard. There are three rear connection ports: one USB 2.0, one 12V power input and the aforementioned ST-4 guide port. You’ll only need to use the 12V power input when the thermoelectric cooling is on. The G3 is not a standalone camera and has to be connected to a computer to use. The necessary
ST-4 AUTOGUIDING PORT The G3 is not just a great entry-level CCD camera: it can be used as an autoguider if it’s connected to the autoguide port of an ST-4-compatible mount. An ASCOM driver is included on the software disc, so ASCOMcompatible packages such as the popular PHD Guiding freeware autoguiding software can also be used.
SENSOR
ALL PHOTOS: PAUL WHITFIELD
The G3 is fitted with a Sony ICX419ALL sensor, which is behind an optical window that is fully anti-reflection coated. There is no infrared-blocking filter. Controlled by software, the sensor can record exposures from 0.01 seconds up to as long as you need them to be.
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FIRST LIGHT DECEMBER 99
software is supplied on a CD-ROM, and includes an operating system driver, an ASCOM (Astronomy Common Object Model) driver and a control application called Orion Camera Studio. The ASCOM driver allows the camera to be used with any ASCOM-compliant imaging software, such as MaxIm DL or Astroart.
Summer success We used the supplied Orion Camera Studio application for our main image tests. It is a simple but efficient camera control and image processing program, through which you can set parameters such as the duration of an exposure and the camera’s binning mode. Our test period was at the end of the – quite frankly – atrocious 2012 summer, when clear skies were something of a premium. It was a testament to the simplicity of operation of the G3 that we were able to set up quickly and make best use of the few clear nights we did get. We coupled it to a 4-inch, f/9 apochromatic refractor to image our main target, the Dumbell Nebula, M27, in Vulpecula. It’s a beautiful object full of delicate structure and plenty of varied grey tones due to its good range of colour. Focusing the camera was very straightforward. First we imaged the roughly focused star field surrounding M27, then drew a selection rectangle around one of the brighter stars in the frame. This allowed us to define a subframe, essentially reducing the active portion of the chip – the area outside the rectangle is ignored. Next, we set the
A SENSITIVE HEART The G3 is based around a Sony ICX419ALL sensor, which boasts 437,664 pixels (each one 8.6μm x 8.3μm) arranged in a 752x582 grid. The sensor has a peak sensitivity of around 530nm, which is in the green part of the spectrum. Sensitivity falls by one-fifth at the important hydrogenalpha wavelength (656.3nm), which is given off by many emission nebulae. Thanks to the onboard cooling circuit, which can reduce the sensor temperature to 10ºC below ambient, the chip can deliver very low noise images. Data from the sensor is transformed into a 16-bit format by an analogue-to-digital converter, so each greyscale image can contain up to 65,536 grey tones – perfect for all those delicate, wispy bits of faint nebulosity. Camera sensitivity can also be increased, at the expense of pixel
Þ The sensor is most sensitive at 530nm count, by ‘binning’ pixels together. The primary modes are 1x1 (binning off) or 2x2. In 2x2 mode, a block of four pixels works together like a larger ‘super pixel’, but this comes at a cost to spatial resolution.
camera to take repeating 1-second exposures. This allowed us to reactively focus and see the effect on screen almost immediately. With the camera set up and ready, we tried a variety of different exposures and settings on M27. The results were remarkably noise free and showed a respectable sensitivity. A 10-second ‘finder’ exposure certainly showed the main form of the nebula well. The longest exposure in our test regime was 15 minutes, which we took simply to see how >
SKY SAYS… Our shots of M27 were remarkably noise free and showed a respectable sensitivity
COOLING Thermal noise is a serious issue in digital imaging, manifesting itself as an ever changing and unwanted pattern in the background of an image. The G3 contains a thermoelectric cooling circuit that can rapidly drop the chip’s temperature to 10ºC below ambient. A built-in fan helps achieve this quickly.
COOLING OFF
COOLING ON
Þ These two dark frames – shots taken with the lens cap on – reveal the difference that the cooling makes skyatnightmagazine.com 2012
100 FIRST LIGHT DECEMBER
FIRST light T-THREADED APERTURE The camera’s aperture is T-threaded, which is common in astronomical eyepiece adaptors. The camera is supplied with a 1.25-inch eyepiece barrel, which allowed the sensor to be fully illuminated without vignetting issues.
SOFTWARE The drivers and control software needed to operate the camera are supplied on a CD-ROM, and can be installed and run on Windows XP, Vista or 7. An ASCOM driver is also supplied, which allows you to operate the camera through third-party ASCOM-compliant imaging applications.
SKY SAYS… Now add these:
PAUL WHTFIELD, PETE LAWRENCE X 2
> deep the camera could go. What we were hoping for
were hints of the faint outer envelope of nebulosity that surrounds M27. What we got back, it has to be said, wasn’t really that conclusive. The camera struggled with this admittedly rather extreme test. The G3 is an excellent entry-level astronomical CCD camera. It’s light, more sensitive than a DSLR, reasonably affordable and delivers crisp, clean and detailed results. If you want to use this camera for full-colour imaging you’ll need to invest in a set of LRGB filters. A filter wheel would also be useful for smooth and quick filter changes if you want to go down this route. It’s not a competitor for the models in the higher end of the market, but great value for money as an skyatnightmagazine.com 2012
introduction to serious deep-sky imaging. And, if you later decide to upgrade to a more advanced primary CCD you’ll still get some use out of the G3 as a guiding camera, so long as you have an ST-4-compatible mount. S
VERDICT BUILD AND DESIGN CONNECTIVITY EASE OF USE FEATURES IMAGING QUALITY OVERALL
★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★★
1. Nautilus motorised filter wheel (holds seven 1.25-inch filters) 2. LRGB 1.25-inch filter set 3. MaxIm DL Pro version 5
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Books New astronomy and space titles reviewed
How to Build a Habitable Planet
THINKSTOCK
Charles H Langmuir and Wally Broecker Princeton University Press £27.95 HB This book has a seductive title and a beautiful cover: an artwork of Earth and the Moon in the blackness of space. But the 718 pages of this mighty volume are the book concentrates a lot on geochemistry not a straight read. It’s a college-level and geophysics – not all that surprising, textbook. Revised and updated from given the authors’ backgrounds. Broecker’s original of 1984, it forms the You would need to be studying A-level basis of a course that’s been taught at maths to get the most out of this book: Harvard for the past six years. there are equations and graphs The authors – Earth scientist sprinkled throughout. The Broecker and geochemist text, which is accessible Langmuir – have taken but sophisticated, is on a mighty task. You university level, but the cannot underestimate summaries at the end the accuracy of their of each chapter are scholarship, or its very succinct and thoroughness. But if helpful. Plus, there’s you are looking for a an excellent glossary popular, accessible and recommended book on the subject, supplementary reading. this is not a narrative For someone who is read – it’s a series contemplating doing science of lectures. Some prerequisites for at college, it’s a fascinating How to Build a Habitable habitable worlds may be book to dip into. It will Planet has been hugely expanded common; others, less so also introduce the way that from its first edition. In 1984, academic information is handled, making dark matter was virtually unknown, it a good primer to learning the kinds hydrothermal vents were unexplored of concepts that will be studied. and no exoplanets had been discovered. This ambitious tome will give you a feel The book kicks off with scientific for the intricacies of science across all the reductionism as a key to understanding disciplines – and how they are interlinked. the Universe; it then moves on to chaos Just don’t attempt to read it all at once! theory, then the Big Bang and the formation of the elements. The other ★★★★★ chapters (there are 21 in all) cover Earth’s birth, the processes leading to life, HEATHER COUPER is an astronomy broadcaster and writer catastrophes and climate change, and the future of humankind in the wider context of the Galaxy. If you’re primarily Reader price: £22.99 subscriber price: £21.99 interested in astronomy, you’ll find that P&P £1.99 Code: S1112/1 skyatnightmagazine.com 2012
RATINGS ★★★★★ Outstanding ★★★★★ Good ★★★★★ Average ★★★★★ Poor ★★★★★ Avoid You can order these books from our shop by calling 01803 865913
2 MINUTES WITH CHARLES LANGMUIR Is there a basic ingredient list for building a habitable world? You need a universe and the particular laws of element formation that lead to suns and planets. You need a star with a mid-way position in its galaxy and a planet in the habitable range of its star. The planet has to have enough volatile elements to make an ocean and atmosphere, and have the ingredients for life. Those are likely rather common conditions in our Universe. After that there are many questions. Earth, for example, has a large moon that helps to stabilise its rotation, and has plate tectonics, which appears to be central for a stable planet. Are these necessary and common elsewhere? Do you think that Earth is the only habitable planet in the Solar System? There may be some primitive life elsewhere that’s analogous to microbes on Earth today. Or there may have been such life on Venus or Mars much earlier in the history of the Solar System. What does the future hold for the habitability of Earth? It depends on us! If we die out, less capable forms of life will endure, particularly the microbes. Ultimately, another intelligent life form would probably evolve. But they would find a planet that had been stripped of its resources — no more fossil fuels, for example. In that case there would not be the opportunity for the development of a technological civilisation, which depends on access to energy. CHARLES LANGMUIR is a professor of geochemistry at Harvard University
BOOKS DECEMBER 103
The Star Book – How to Understand Astronomy Peter Grego David and Charles £12.99 PB Peter Grego is an experienced freelance writer with a particularly keen interest in lunar observing. However, in The Star Book, he brings the rest of the Universe into sharp focus. Aiming at a wide readership, he takes us on a journey exploring the heavens in an easy to read style that engages the attention without overwhelming with too many facts and figures. Basics such as a overview of the history of astronomy, and the lives and deaths of stars are covered in the early chapters, then the book moves on to the main objects that populate the Universe such as star clusters, nebulae and galaxies. The final section covers the Solar System and is followed by a useful glossary. A good proportion of the book is comprised of wide-field charts for both
Space Atlas James Trefil National Geographic Books £29.99 HB Although this atlas has maps, it is as much a bright and colourful guide to the Universe, including plenty of pretty pictures from big, ground-based telescopes and space probes. The text is an easy read, but interesting and informative, taking readers through the Solar System and out to the most distant galaxies and beyond. It establishes how Greek philosophers turned ancient ideas of a flat Earth into more scientific models and how our understanding was advanced further thanks to three pioneering astronomers – Copernicus, Bessel and Hubble, who are oddly described here as ‘spearmen’ because they increased the size of the known Universe as if each had hurled a spear out from the previous known boundary. The ‘atlas’ part of the title is met by a series of maps, starting with the planets
OK BO F TH E
the northern and southern hemispheres, O NTH accompanied by useful O M information on selected constellations of interest, such as the best deep-sky objects to look for. The main charts show the horizons for several locations, but one of these is dark blue and difficult to see against the black background. Turning to the pages that detail individual constellations, the coverage is good. Orion, a resplendent constellation, has the stunning Orion Nebula which is mentioned in the text, yet the photo chosen for Orion shows the hard to see Horsehead Nebula. We also would have liked to have seen charts accompanying each constellation but appreciate space in a book of this size is tight. These are however minor points; The Star Book is an enjoyable read and it would make a fine present to anyone interested in discovering the Universe.
★★★★★ PAUL MONEY is Sky at Night Magazine’s reviews editor Reader price: £11.99 subscriber price: £10.99 P&P £1.99 Code: S1112/3
and many of their moons. Perhaps our own Moon, an easy observing target, could have been spread over more maps in view of how much we know about its features: it is confined to two, one for the near side and one for the far. There are also maps for the inner and outer Solar System, displayed on a rather complex grid, an exoplanetary system and various regions of the Universe, with additional text on how it has evolved and expanded. The night-sky charts are disappointing. The heavy grid and constellation boundaries clutter up the four hemispheres covering the northern and southern sky, making it hard to get your bearings. Want to find Pegasus? You’ll need to turn the ‘summer-fall’ page upside down. And poor Orion is split between two different pages since it has one half in the north and one in the south. Nevertheless, the illuminating text provides a reason to buy.
We are the Martians Giovanni F Bignami Springer £26.99 PB Look in the mirror. What you see could very well be a distant descendant from a Martian microbe. After all, Martian meteorites are known to land on Earth. Billions of years ago, they could have seeded our planet with primitive organisms from the Red Planet. This is just one of the many speculative ideas and hard scientific facts that are described in Giovanni Bignami’s little book. In just over 100 pages, the author, a well-known Italian astrophysicist and past president of the Italian Space Agency, takes readers on a crash course in cosmology and astrobiology. In clear but very condensed prose, Bignami introduces the origin of the Universe, the elements, planets and life, going on to present a status report on our current knowledge about interstellar organics, extrasolar planets and the search for extraterrestrial life. It’s always great when an exciting field of science is being presented to a wider audience by one of its practitioners, but Bignami concedes that he himself is a relative outsider to biology. Also, he apparently lacks the explanatory skills of Brian Greene, or the poetic writing style of Carl Sagan. What remains is more comparable to a volume of lecture notes than a popular science book. To make things worse, the translation from the original Italian is extremely poor and the design of the book is, well, almost non-existent. The author, the topic, and – especially – the reader deserve much better than this rather sloppy and disappointing booklet.
★★★★★
★★★★★
GOVERT SCHILLING has written more than 40 astronomy books
PAUL SUTHERLAND is a journalist and astronomy writer
Reader price: £23.99 subscriber price: £22.99 P&P £1.99 Code: S1112/2
Reader price: £27.99 subscriber price: £26.99 P&P £1.99 Code: S1112/4
skyatnightmagazine.com 2012
104 GEAR DECEMBER
Gear
Vincent Whiteman rounds up the latest astronomical accessories
1
4 1 Orion SteadyPix Telescope Photo Adaptor for iPhone
Price £59 • Supplier The Widescreen Centre 020 7935 2580 • www.widescreen-centre.co.uk Use this adaptor to clamp your iPhone onto an eyepiece, helping you capture images of the Moon and bright planets. The adaptor is compatible with the 3G, 3GS, 4 and 4GS handsets.
2 3x Compact Barlow Lens
Price £19.99 • Supplier Nipon Scope & Optics 0844 3187890 • www.nipon-scope.com Triple your magnification with this 1.25-inch fit 3x lens attachment. It’s fully multicoated to improve contrast and fits PL16, PL20, PL26 and PL32 eyepieces from Nipon.
5
3 Orion Wide Side-by-Side Plate
2
Price £182 • Supplier SCS Astro 01823 665510 • www.scsastro.co.uk
This saddle plate allows you to attach two scopes to a single mount. The plate fits Losmandy-style dovetail saddles and accepts optical tubes with a wide dovetail mounting plate.
4 Sky-Watcher Explorer-130PDS
Price £179 • Supplier Optical Vision 01359 244255 • www.opticalvision.co.uk This 5-inch Newtonian reflector has a 2-inch, 10:1 dual-speed Crayford focuser. The f/5, 650mm focal length telescope comes with a 6x30 finderscope and 28mm eyepiece.
3
5 Optical Hardware Binocular Tripod Adaptor Price £13.99 • Supplier Northern Optics 01724 782022 • www.northernoptics.co.uk
Suitable for Porro prism binoculars and weighing just 80g, this metal tripod adaptor can support binoculars of up to 70mm in aperture.
6 Revelation 2-inch to 1.25-inch Adaptor
Price £21 • Supplier Rother Valley Optics 01909 774521 • www.rothervalleyoptics.co.uk
This attachment narrows a scope’s 2-inch opening to a 1.25-inch fit, allowing you to use your 1.25-inch eyepieces and accessories.
skyatnightmagazine.com 2012
6
106 EXPERT INTERVIEW DECEMBER
WHAT I REALLY WANT TO KNOW IS…
How can we analyse ancient galaxies? Edo Berger used an exploding star to shed light on the composition of a galaxy 9.5 billion lightyears away INTERVIEWED BY PAUL SUTHERLAND
O
ne of the big questions for astronomers is how galaxies evolved from the early Universe to the present day. Galaxies in our local region of space are relatively easy to find. They’re bright and we can study them in detail to see what they’re made of. The challenge comes when we look much farther away and so farther back in time. Those distant galaxies are much fainter and more difficult to study. We are trying to understand galaxy composition in terms of different types of metals – astronomers refer to every element other than hydrogen and helium as a metal. In the early Universe, before several generations of star formation had taken place, we should see fewer metals. But as galaxies become fainter, it becomes harder to measure their metal content using current methods.
Genetics in light To determine what a galaxy is made of, astronomers usually study the spectrum of its light. By examining the chemical fingerprint in light we can study, for example, the relative ratios of oxygen and hydrogen. This becomes extremely challenging beyond a distance of eight billion lightyears. It is practically impossible to study galaxies in the early Universe because the light is too faint to break up into a spectrum, even by the most powerful scopes. Scientists have therefore had to look for other ways to study metal content. One way has been to look at the spectra of really bright, distant light sources such as quasars – active galactic nuclei that emit large amounts of energy as electromagnetic radiation. The hope is that somewhere between the quasar and us will be a galaxy that absorbs a small portion of the quasar’s light and so leave its own fingerprint in it, revealing its metal content. The problem has been that all the action in a galaxy – such as star formation – tends to happen in the main disc. Most of the time a quasar’s light skyatnightmagazine.com 2012
Supernovae can shine so bright that they appear as stars; this one is in the outer reaches of the Pinwheel Galaxy, M101
ABOUT EDO BERGER Edo Berger is an associate professor of astronomy at the Harvard-Smithsonian Center for Astrophysics. He has a special interest in explosive objects and what they can tell us about the Universe
shines through an intervening galaxy’s halo, which is less interesting. So to study the main part of a remote galaxy, you need a bright light source that is embedded in the disc itself. To do this, we’ve been using supernovae, the violent explosions of stars at the ends of their lives, or gamma-ray bursts. To detect gamma-ray bursts you need satellites that cost hundreds of millions of dollars. To find supernovae we use the ground-based Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) in Hawaii, which is much cheaper. Supernovae also stay bright for longer, so we have more time to obtain data. In November 2011, we were alerted to a new supernova, PS1-11bam. Not only was it one of the most distant supernovae ever found, at a distance of about 9.5 billion lightyears, but it was also one of the most luminous. Why it was so bright remains a puzzle, but we were glad to have it! When we took our spectrum, we found fingerprints of two metals in particular, magnesium and iron. These produce some of the strongest imprints, so are the easiest to detect. We are certain that there are other metals in the host galaxy like carbon, oxygen, silicon and nickel. Compared to galaxies examined using quasar light, there was more magnesium and iron. Compared to others examined using gamma-ray bursts, the amount of metals was a little lower. This told us that the galaxy we saw was a ‘normal’ galaxy, rather like the Milky Way would look if we put it 9.5 billion lightyears away. To find such a galaxy might at first seem boring, but I think it tells us that at those distances there are galaxies that have a range of distributions of metal content. Galaxy formation is not uniform and they do not all grow at the same rate. This seems a promising avenue to explore to help us probe the Universe 90 per cent of the way back to the Big Bang – we just need to find more of those faraway supernovae! S
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SOUTHERN HEMISPHERE IN DECEMBER With Glenn Dawes
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Travel down the river (17° southwest) to face-on spiral galaxy NGC 1232, pictured left (RA 3h 10m, Dec. –20° 35’). It has an obvious, brilliant nucleus 1 arcminute in diameter, but although it is mag. +9.9 the remainder of the galaxy is quite diffuse, so you’ll need dark, transparent skies to glimpse it. An 8-inch telescope shows some mottling, hinting at the spiral arms and the gaps between them.
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Virginis); the slightly brighter ‘star’ to the lower right is Saturn. This month opens with brilliant Venus 4° to the lower right of Saturn, with Mercury a few degrees below Venus. As December progresses Saturn rises in the morning sky, separating from Venus.
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Mars is low in the western twilight, by which time Jupiter will have already appeared in the east. If you want to catch Uranus and Neptune try early in the evening, low in the northwest. At dawn (4.15am) look east to find mag. +1.0 Spica (Alpha (a)
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The constellation of Eridanus, the River, has its headwaters near Orion. Move 15° to the left (west) of mag. +0.2 star Rigel (Beta (a) Orionis) to reach mag. +4.0 double star Omega Eridani, then 5° up (south) to find planetary nebula NGC 1535. This mag. +9.4, 30-arcsecond diameter, slightly oval blob shows an evenly illuminated grey haze in small scopes. Through larger instruments it looks pale blue.
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Look south for three prominent stars, mag. –0.7 Canopus (Alpha (a) Carina), mag. +0.5 Achernar (Alpha (a) Eridanus) and mag. +1.2 Fomalhaut (Alpha (a) Piscis Austrini). They lie in a straight line and mark three distinct regions. Canopus is rising in the southeast, heralding the return of the southern Milky Way. Achernar being high means it’s a great time to view the star clusters and nebulae of the Magellanic Clouds, while Fomalhaut’s location, well out of the galactic plane, is a signpost for galaxies.
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The Geminid meteor shower is one of the stronger and more consistent annual showers, with peak zenithal hourly rates reaching as high as 120 per hour. It’s best seen from the northern hemisphere, but has produced great displays down under in the past. The Geminids are visible from 30 November to 18 December, with maximum expected on the 13th when, happily, the morning sky will be moonless. The radiant, near mag. +1.9 Castor (Alpha (a) Geminorum) crosses the meridian (due north) around 2am.
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STARS AND CONSTELLATIONS
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