Innholdsfortegnelse for May/Jun 2016 i Australian Sky & Telescope

The Moon is usually the first astronomical body that astronomers get to know. Just ask Galileo, who aimed his telescope at the lunar surface and set off a scientific revolution that would eventually sweep away aeons of celestial superstition and the Earth-centric model of the cosmos. The Moon is up there in the sky, unchanging, sometimes at night, sometimes during the day, and the beauty of it is that you don’t need a telescope to begin your initial reconnaissance — the naked eye alone is enough. But progression to binoculars and then a telescope reveals a world full of surprises — mountains, valleys, rilles, craters big and small, and majestic sweeping plains. There’s enough there for a lifetime of study. It’s a great target for photography too. And with almost…

Researchers are circling back to the idea that carbon dioxide ice might be responsible for some or all of the gullies on Mars. In 2000, images from NASA’s Mars Global Surveyor revealed hundreds of these features, trailing down crater rims all over the Red Planet. They looked geologically fresh, cut into older terrain yet largely free of erosion. These gullies are different from (and much larger than) the occasional, seasonal trickles of salt-infused water seen elsewhere on the surface, which create the so-called recurrent slope lineae. Initial speculations focused on the idea that water was seeping out onto the surface and cutting little channels as it flowed downslope. Yet many gullies occur in frigid polar regions or on heavily shadowed slopes facing toward the poles. The ‘gully debate’ reignited last…

The Infinity breaks the barrier between visual observing and astrophotography. It combines the experience of observing at the eyepiece with a level of depth and detail that would traditionally be the result of several hours processing. This takes a camera that's sensitive enough to capture faint details on distant objects, and fast enough to do it in real time. It then takes our powerful, intuitive software to bring stunning views of the night sky to a screen in just seconds. This recreates the feel of observing in the field through a very large telescope, only using much more modest equipment. You stay connected to the night sky, watching satellites drift across your field of view, while viewing objects previously out of reach to all but the most powerful eyepieces and…

Astronaut Scott Kelly and Cosmonaut Mikhail Kornienko have now returned triumphant from their ‘Year in Space’. Since March 2015, these men had orbited our planet aboard the International Space Station (ISS). It’s easy to take the ISS for granted, and I’ll admit at times I’ve grumbled about its share of the NASA budget compared with that of my own pet planetary probes. But the Year in Space has rekindled the idealistic and romantic excitement, fuelled by the Apollo missions and science fiction, which as a kid had me imagining we would soon be widely inhabiting the Solar System. Kelly and Kornienko used themselves as experimental subjects, gathering valuable data on human responses and adaptations to long-duration spaceflight that will be key for missions to Mars or elsewhere. Life has evolved…

Where Leo waits King Sol in dog-days’ reign And Regulus shines diamond-like and bright, When springtime wakes and summer smiles again Till harvest moon beams yellow in the night; Six suns, with four stars sparkling in its train, Like question-mark which faces to the right. Or secret symbol written clear and plain, A starry sickle glitters in men’s sight. — Charles Nevers Holmes, The Starry Sickle, 1916 Our king of beasts, Leo, the Lion, reigns supreme in the northern part of our skies at the moment, watching over his domain from just north of the celestial equator. The constellation’s most distinctive part is an asterism known as the Sickle of Leo. The Sickle’s highly curved blade is open toward the west, and diamond-like Regulus marks the end of its handle.…

Fork-mounted Schmidt-Cassegrain telescopes have been around for more than half a century. That’s a sobering thought for those of us who vividly remember the first advertisements for them appearing in magazines in the 1960s and their popularity growing almost explosively after Celestron introduced an attractively priced 20-cm model a few years later. By the early ’80s, Meade too was building Schmidt-Cassegrains, and the familiar silhouettes of stubby-tube, fork-mounted telescopes were ubiquitous along the skyline at every star party large and small. Schmidt-Cassegrains were the telescope to own whether your interests lay in visual observing, astrophotography, or both. Frequent improvements, especially ones made for astrophotographers, occurred as Celestron and Meade volleyed design tweaks back and forth vying for market share, all the while keeping the telescopes priced within the reach of…

Royal Astronomical Society of NZ Conference May 20–22 Annual meeting of New Zealand’s astronomers hbastrosoc.org.nz/rasnz-conference-2016/ South Pacific Star Party May 5–8 Annual star party hosted by the Astronomical Society of NSW asnsw.com/spsp Queensland Astrofest July 29 – 7 August Lions Camp Duckadang, Linville, Qld Long-running annual star party www.qldastrofest.org.au Public Open Nights in Sydney August 12–13 The Sutherland Astronomical Society will throw open its observatory’s doors to the general public. Always a great occasion. sasi.net.au National Science Week August 13–21 Various activities around the nation www.scienceweek.net.au Siding Spring Open Day October 1 Australia’s largest optical telescope throws open its doors to the public. starfest.org.au StarFest 2016 October 1–2 A weekend of activity at Coonbarabran during the Festival of the Stars starfest.org.au VicSouth Desert Spring Star Party 2016 October 28 –…

A few hundred million years ago, a small galaxy had a fender-bender with the Milky Way. Even as it fled the crime scene, it sent ripples coursing through the Milky Way’s disk. Now with the help of a trio of brightly pulsating stars, Sukanya Chakrabarti (Rochester Institute of Technology) and colleagues say they have found the fugitive dwarf galaxy. Last year, Chakrabarti and her team found four stars located toward the constellation Norma — the exact spot where, back in 2009, she and Leo Blitz (University of California, Berkeley) had predicted the runaway galaxy is hiding. The astronomers hoped the four stars were Cepheids, standard candles that regularly expand and contract at a rate directly related to their intrinsic brightness. If so, the team would be able to use the…

Astronomers tracking a distant quasar over a span of 13 years have reported that all signs of it have disappeared. The quasar, known as SDSS J1011+5442, was first detected in 2002. A follow-up spectrum collected the next year showed all the signs of hot gas feeding a typical, ferociously gobbling supermassive black hole sitting at the centre of a galaxy. The quasar’s brightness declined steadily over the next decade, far more systematically than usually happens with such objects. When Jessie Runnoe (Penn State University) and colleagues observed the quasar again as part of the Time Domain Spectroscopic Survey in 2015, they took a visible-light spectrum of the beast’s disk of gas. They found nothing — almost all signs of the quasar had vanished. Instead, they saw only a relatively ordinary…

Microscopy: Biological samples bend a microscope’s beam of light in unpredictable ways. By first focusing the light into a glowing point, scientists can see how it warps as it passes through intervening tissues and correct for the distortion. Ophthalmology: Ophthalmologists struggle to see past the fluid inside the eye to make out minute details in the retina. But with adaptive optics, they’re able to see the finer features, allowing them to diagnose potential eye diseases early enough to prevent them. Military: It took more than 25 years, but it seems the military’s goal to utilise laser weapons has finally left the realm of science fiction. Engineers can now pre-distort a laser beam to cancel out atmospheric turbulence and focus with precision on a target.…

The digital imaging revolution has taken astronomy by storm. Spectacular images recorded by amateurs using digital single-lens reflex (DSLR) cameras, specialised planetary cameras and large-format CCDs dominate the pages of this magazine. But the imaging devices you most likely own are smartphones, tablets and compact ‘point-and-shoot’ cameras. Surprisingly, these simple devices are capable of producing pretty, even stunning images of our nearest neighbour, the Moon. It’s not quite as easy as just walking up to the eyepiece and snapping away — but that’s the general idea. Whether you have a smartphone or tablet (which usually have small, fixed-focus lenses) or a much more versatile compact camera or DSLR, all employ a similar set of operational modes. Some have a ‘manual’ setting, and that’s preferable to the ‘automatic’ mode, which tends…

If there’s one big category of deep sky object that binoculars are best at showing, it’s undoubtedly open clusters. While most globular clusters and galaxies more or less look alike through binos (with a few notable exceptions), just about every open cluster has its own character. They run the gamut from big, bright and splashy, to small, dim and hazy. You can sample some of this range by aiming your binoculars at the Puppis Messier pair, M46 and M47. An easy way to find M46 and 47 is to start from Canis Major. Draw a line from Beta (›) Canis Majoris (or ‘Mirzam’) through Sirius, and continue on for twice the distance between the two stars. That brings you to the cluster duo. Both objects comfortably fit in the same…

Viewing meteor showers is free, it’s fun, and it’s a reminder that there is a vast universe out there. A shower occurs when Earth passes near a comet’s orbit and the debris particles left in the comet’s wake hit Earth’s atmosphere. The dates of showers are predictable, so all you have to do is hope for the right conditions and wear the appropriate gear to keep warm. It’s also important to select a suitable viewing spot. Preferably, there should be an unobstructed view of the sky, so beware of trees, buildings, houses and anything else that might block your view. Most of all your chosen viewing spot should be as dark as possible, away from sources of artificial light. Don’t forget to check the weather forecast and Moon conditions, as…

Lunar photography has always been a relatively simple procedure: aim your telescope, focus and snap a bunch of pictures. Indeed, the same basic technique used in 1840 by John Draper when he shot the first lunar daguerreotype remains essentially unchanged for everyday full-disk images. But taking detailed close-ups of crater fields is a different nut to crack. Recording sharp lunar images used to require an enormous amount of effort and luck. Fortunately, with the advent of electronic imaging and frame stacking, that has all changed. These days we use the established technique of ‘lucky imaging’ — recording a series of images in rapid sequence, and then combining the sharpest frames into a final, high-resolution result. This enables amateurs with modest equipment to produce lunar images that easily surpass the quality…

Astronomers are ramping up their search for exoplanets orbiting the nearest star to our Solar System. The Pale Red Dot initiative, led by the European Southern Observatory, is a campaign to examine the red dwarf star Proxima Centauri for exoplanets using the radial velocity method, which teases out the signal of a planet tugging on its host star. You can follow the Pale Red Dot campaign on the project’s website, palereddot. org , or by following the Twitter hashtag #PaleRedDot. Meanwhile, Proxima Centauri’s passage in front of a background star in February gave the Hubble Space Telescope an opportunity to look for microlensing events . These are small spikes in the background star’s brightness that a planet orbiting…

Limit on black hole gluttony. Once a black hole reaches about 50 billion times the mass of the Sun, the disk of gas that acted as its dinner buffet begins to crumble apart. Andrew King (University of Leicester, UK) presents this conclusion in the journal, Monthly Notices Letters of the Royal Astronomical Society . A more massive black hole will have a larger disk feeding it than a smaller hole will. But King calculates that, above the limit, the disk’s gas will collapse into clumps, forming stars. To continue growing, the black hole would need to swallow clumps (or stars) whole. Since the glow from those disks is what enables observers to ‘see’ these dark objects, more massive black holes might be truly invisible: astronomers would need…

Measuring distance is one of the central problems in extragalactic astronomy. Though astronomers can use redshifts to sort galaxies by distance — a higher redshift means a galaxy’s light has travelled a longer way through our expanding universe — redshift does not measure distance directly. Standard phenomena provide other ways to measure distance. Standard candles are objects of known luminosity. If we measure their apparent brightness and know their intrinsic brightness, we can infer their distance. Standard rulers are objects of known size. We can infer their distances by their apparent size on the sky. This same concept explains why you can still judge distances even with one eye closed as long as you know how intrinsically big something is. Accurate distance measures are vital to determining the universe’s age…

And you would cause the sun to see your light And then be shamed You cover darkness with a thousand secret flames With your love, oh my love, oh my love, my love… — Michael Dunford and Betty Thatcher, The Young Prince and Princess In February’s column, I discussed the desirability of observing a thousand stars and how to go out and find them. This month, I look at the two sides — practical and mystical — of such observations. The mystical calls for us to see the stars as “a thousand secret flames”. To imagine the stars as fire is a potent idea, even if the truth of it is that they’re nuclear fires, producing energy by fusion rather than combustion. In the 19th century, scientists calculated that even…

Telescope users should plan to catch Jupiter right around the end of twilight, while it’s still high on the meridian or just past it. Below are the times, in Universal Time, when Jupiter’s Great Red Spot should rotate across the planet’s central meridian. The dates, also in UT, are in bold. April 15, 5:28, 15:23; 16, 1:19, 11:15, 21:10; 17, 7:06, 17:02; 18, 2:57, 12:53, 22:49; 19, 8:44, 18:40; 20, 4:36, 14:31; 21, 0:27, 10:23, 20:18; 22, 6:14, 16:10; 23, 2:05, 12:01, 21:57; 24, 7:52, 17:48; 25, 3:44, 13:39, 23:35; 26, 9:31, 19:27; 27, 5:22, 15:18; 28, 1:14, 11:09, 21:05; 29, 7:01, 16:56; 30, 2:52, 12:48, 22:44. May 1, 8:39, 18:35; 2, 4:31, 14:26; 3, 0:22, 10:18, 20:14; 4, 6:09, 16:05; 5, 2:01, 11:56, 21:52; 6, 7:48, 17:44; 7, 3:39,…

These observing tips will help you see more with your binoculars no matter the quality of your skies. Go high in the sky. When objects are transiting, you’ll experience less atmospheric interference. This helps even under dark skies, but it’s crucial if there’s light pollution. Get comfortable. For observing well above the horizon, this usually means reclining or lying down. A chaise lounge, sleeping bag or blanket thrown over a picnic table, or the bonnet of a car, or just on a clean, dry patch of grass — all of these can serve as observing ‘platforms’. Brace yourself. Or at least brace your binoculars against something. I’ve had good success using a monopod while reclining, trapping the far end between my feet. It may seem clunky, but…

A lot of Dobsonian-style telescopes have appeared in this column over the years, and for good reason. They’re popular because they have the potential to deliver plenty of aperture in an effective, simple-to-use package. But another design that shares these attributes is the so-called ball scope. Indeed, but for one significant detail, they would probably be more popular than Dobs. And what is that detail? In a word, the ball. More about that in a moment. The attributes of the ball-and-socket design are well demonstrated by this 50-cm, f/3.9 reflector built by amateur telescope maker Pierre Lemay. He describes it as his dream scope, and I suspect his dream is one shared by quite a few readers. For Pierre, the ‘dream’ includes large aperture and motorised tracking in an instrument…