Innholdsfortegnelse for July 2015 i Australian Sky & Telescope

When I was just a wee lad, the whole world was comfortable in the knowledge that our Solar System had nine planets. There was even a bunch of lovely little mnemonics we used to help us remember their order from the Sun – such as ‘My Very Educated Mother Just Served Us Nine Pizzas. Yet some people I know who are in their late 80s were born when there were only eight planets. The difference lies, of course, in the pizzas... sorry, in Pluto. Discovered on February 18, 1930, the tiny, icy globe captured the imagination of the public and the scientific community alike, and made headlines all around the world. But then that was it for a long, long time. Being so distant and so small, not much information…

Comets are reputedly scary things to see in the sky, bringing warning of forthcoming evil events, such as the death of Julius Caesar or the Battle of Hastings. That reputation is generally undeserved. In fact, provided they keep their distance, comets are no more hazardous that the stars that lie far behind them. But occasionally they do get too close for comfort; indeed close enough to collide with us or other planets. Earth has been hit many times, though the scars are now mostly eroded away, and we can still see the results of the impacts on the pristine faces of the Moon or Mercury. (Some of the impacts were by asteroids rather than comets, asteroids being mostly rocky, while comets are mostly icy). Such collisions are, of course rare,…

Scorpius features a wealth of interesting binocular targets for winter nights. One region that is often overlooked includes 2.6-magnitude Beta (в) Scorpii. It forms an attractive triangle with two binocular double stars: Nu (v) and Omega (w) Scorpii. One is as easy as they come, the other is a serious challenge. Compared with telescopes, binoculars have two significant limitations when it comes to observing double stars. First, typical binos operate at magnifications of 7? to 15?. That’s great for wide-field views, but it’s a bit of a handicap for most doubles, which often require plenty of magnification to split. The second disadvantage is that binoculars are most often hand-held, which significantly limits their resolution due to jitter. Fortunately, you can buy or build a binocular mount. (A web search will…

Located to the east and south of the Pointers, Circinus is a small constellation surprisingly full with double stars. Some are easy with 60-mm or 80-mm telescopes; others need more aperture. The first surveyor of doubles in this region was James Dunlop in the 1820s, from his backyard in Parramatta with his rather primitive 9-inch reflector. Alpha Circini, of the 3rd magnitude, is a Dunlop discovery (DUN 166) — a wide and easy pair, the 8th-magnitude stars visible with 60-mm. The primary is yellow, the companion reddish. DUN 169, is about 50 north-northeast of Alpha Centauri. A very wide pair, the stars are bright, magnitudes 6 and 7.5, and provide a colour contrast of white primary and dull orange secondary. It can be seen as a little pair with an…

Nothing imparts the immensity of the universe quite as well as seeing a galaxy cluster through the eyepiece of your telescope, and at 1.1 billion light-years distant the exceedingly faint collection of galaxies that make up Abell Galaxy Cluster 2065 do indeed look far, far away. As you might imagine, light that’s travelled for over a billion years, from galaxies that appear as tiny, barely perceptible smudges, is a difficult yet remarkable sight to see. AGC 2065 is a tough nut. Scopes that can barely see this faint need optimum observing conditions to have any chance to reveal the brightest member galaxies. Large scopes, however, will show multitudes of galaxies, most of which take averted vision to see, so the cluster has to be tackled in sections — and you…

July 2005 Putting Einstein to the test The only way to move forward toward a comprehensive understanding of the universe is to test general relativity to the highest precision possible. Finding even the slightest flaws in the theory will help physicists determine which theory of quantum gravity might work and which can be ruled out. Such advances could lead to a new golden age of physics. A host of new experiments are testing the extreme limits of Einstein’s universe, and astronomical observations are at the forefront. July 2010 Halfway to Pluto In January 2006, NASA’s New Horizons spacecraft sped away from Earth as the fastest spacecraft ever launched. Earlier this year, New Horizons passed the halfway point to its far-flung primary target, the Pluto system. In March 2011, the craft…

The photos are eerie, almost otherworldly: A warped landscape with no signs of life. There are no people, no animals, and no cars in the street. All that’s visible is the still landscape, crowned above by colourful traces of the Sun’s path across the sky. These photographs are known as solargraphs, recorded using the technique known as solargraphy. Their sole purpose is to capture the Sun’s path over a long period of time with a foreground of your choice, for about a half-year exposure. The best part of this technique is it’s cheap and easy to do, and it doesn’t require an expensive camera, telescope or even any developing chemicals. What is solargraphy? Solargraphy is a modern take on pinhole photography, developed jointly by photographers Slawomir Decyk, Pawel Kula and…

WHEN Early June 10 p.m. Late June 9 p.m. Early July 8 p.m. Late July 7 p.m. These are standard times. HOW Go outside within an hour or so of a time listed above. Hold the map out in front of you and turn it around so the label for the direction you’re facing (such as west or northeast) is right-side up. The curved edge represents the horizon, and the stars above it on the map now match the stars in front of you in the sky. The centre of the map is the zenith, the point in the sky directly overhead. FOR EXAMPLE: Turn the map so the label “Facing North” is right-side up. About halfway from there to the map’s centre is the bright star Arcturus. Go out…

Although the starry sky is one of our great loves, most amateur astronomers don’t think of stars as proper deep-sky objects. But why not? They certainly reside beyond the shallow sky (our Solar System), and they’re fascinating objects in their own right. For some remarkable stars that are now well-placed in our sky, let’s visit Serpens Caput, the Serpent’s Head. We might picture this celestial serpent as a diamond python snake, flecked with small stars and inhabiting a regal place in the lofty heavens. Unlike our Sun, most stars dwell in multiple star systems, making them the most popular stars pursued by skygazers. Multiple stars come in a variety of colours, separations and magnitudes that heighten their allure. What better place to start this month’s tour than the incredible system…

Galaxies are social creatures — they’ll congregate in groups of any size from pairs and threesomes, to clusters and superclusters. Dedicated observers of galaxy groups are familiar with Paul Hickson’s Compact Groups of Galaxies and George Abell’s Rich Clusters of Galaxies. If these match your observing interests, let me introduce you to the 1979 catalogue of Isolated Triplets of Galaxies by principal investigators Valentina Karachentseva (Astronomical Observatory of University of Kiev, Ukraine) and Igor Karachentsev (Special Astrophysical Observatory, Russia). This catalogue contains 84 trios (often called the KTG or K-triplets) found by visual inspection of the Palomar Observatory Sky Survey plates. A group was considered isolated if the nearest ‘significant’ neighbour was at least three times as far away as the separations of the components. A 1998 follow-up study using…

This year's Victorian Astronomical Convention (VASTROC) was hosted by the Bendigo and District Astronomical Society, and held at the Discovery Science and Technology Centre in Bendigo, Victoria. The convention began on the Friday night (April 17) with a social function and a session at the venue’s planetarium. A planned sidewalk astronomy program at the same time was unfortunately washed out by rain. A full program of interesting topics was presented on the Saturday, with the two keynote addresses being Astronomical spectroscopy’ by Ken Harrison and ‘Night sky photography’ by well-known astrophotographer Phil Hart. Other sessions covered a diverse range of topics: astronomy in the suburbs, cloud forecasts for astronomers, studies of the Solar System at infrared wavelengths, black holes, and upcoming solar eclipses. Ian Sullivan showed interesting images from his…

Two teams of astronomers went panning for gold in the Southern Hemisphere sky — and both struck it rich. Between the two, the teams discovered nine candidate dwarf galaxies near the Milky Way. Future observations will determine whether these are really dwarf galaxies or merely globular star clusters. The teams both used data from the Dark Energy Survey, an optical and near-infrared project at Cerro Tololo Inter-American Observatory in Chile. Combing through the first year of images taken by the Dark Energy Camera, a team led by Keith Bechtol (University of Chicago) found eight clusters of stars well outside the boundaries of the Milky Way; the second team, led by Sergey Koposov (University of Cambridge, UK), found the same eight dwarf candidates, plus one more near a gap in the…

Milky Way has ripples. Astronomers have detected four undulations in our galaxy’s disk. Previous observations had revealed clumps in the density of stars at the disk’s outermost edge, part of two structures now called the Monoceros Ring and, beyond it, the Triangulum Andromeda Stream. But a second look at Sloan Digital Sky Survey (SDSS) observations suggests that the disk actually has four ripples, with two more lying between us and the Monoceros Ring. The closest is about 6,000 light-years out from the Sun, with each subsequent structure lying roughly 6,000 light-years beyond the previous one. The lumps vary between being above and below the disk, like the ripples in corrugated cardboard. There also appears to be a vertical ripple in the disk, Yan Xu (National Astronomical Observatories of China) and…

Many of today’s astronomers were still in primary school when the space shuttle Discovery carried the Hubble Space Telescope into orbit 25 years ago. Some weren’t even born yet. To them, Hubble has always been around. Indeed, we’ve all grown familiar with the pretty pictures and revolutionary results of the most successful telescope in the history of astronomy. Even for veteran researchers, it’s hard to remember how different the science of the universe looked before 1990. It’s also hard to remember that back then, many scientists were pretty skeptical about the space telescope, which traces its origin back to a 1946 (!) proposal by astronomer Lyman Spitzer (1914-97). Over the years, Hubble experienced huge delays and cost overruns — some US$2 billion in 1990 dollars had been spent by the…

Beyond any planet that’s ever been explored before lies the frozen ‘Third Zone’ of the Solar System: the Kuiper Belt. It’s dark, cold and sluggish, a place so remote that its small, icy inhabitants take hundreds of years to complete a single orbit of the distant, dim Sun. We’ve only seen a handful of Kuiper Belt objects from Earth — and none of those as anything more than tiny, vague smudges. But after nearly a decade of interplanetary travel, NASA’s New Horizons spacecraft is about to change the status quo. Now we’re about to see, up close, the region’s most famous member: Pluto. New Horizons is not the first spacecraft to traverse this region of space, but it will be the first to study any of its denizens. The spacecraft…

PORTABLE PIER iOptron’s new Tri-Pier heavy-duty portable pier combines the stability of a permanent pier with the flexibility of a tripod. Manufactured from aluminium and stainless steel, the 14.5-cm-diameter pier has a total load capacity of 100 kg, and supports iOptron’s iEQ, CEM and MiniTower drive heads, as well as the company’s ZEQ25 mount (with optional pier extension). The three legs have an 85mm range of travel to enable users to quickly level their mount for greater Go To pointing accuracy. The Tri-Pier weighs 11.6 kg, is adjustable to heights between 79.5 and 109 cm, and collapses to 32.5 by 65 cm when folded for travel. iOptron.com  and local dealers LOGGING APP Emerald Bay Software brings you StarLog, an observing logbook app for your iPad. StarLog lets you log, track…

Bucking the trend of converting regular Dobsonians into truss-tube models, George Golitzin has gone the other way, transforming his 32-cm truss-tube Dob into one with a conventional tube. Having performed the same operation myself, I had a pretty good idea why he did it. There’s no denying the virtues of a well-made truss-tube Dobsonian. They combine big-aperture performance with lightweight portability. And yet, for all their many virtues, truss scopes do have disadvantages. They can be fussy to balance, a chore to assemble in the field, and often suffer from poor baffling. And I’ve seen more than a few such scopes that sacrificed rigidity for reduced weight. In George’s case, he grew dissatisfied with the performance of his scope’s original configuration. “The structure was pretty shaky, mainly because the truss…

CWAS Astrofest July 18-19 Annual conference held in Parkes (home of 'the Dish'), including the David Malin Awards cwas.org.au/Astrofest/ Queensland Astrofest August 7-16 Annual star party qldastrofest.org.au National Science Week August 15-23 Lots of public astronomy activities held around Australia scienceweek.net.au StarFest 2015 October 2-4 Held at Coonabarabran, home to Siding Spring Observatory, there'll be three days of activities during the Festival of the Stars starfest.org.au Siding Spring Open Day 2015 October 3 Australia's largest optical observatory throws open its doors to the public starfest.org.au Border Stargaze October 8-11 Amateur astronomy star party near Albury on the NSW-Vic border asaw.org.au/bsg VicSouth Desert Spring Star Party November 6-9 Annual star party hosted by the astro societies of Victoria and South Australia vicsouth.info National Australian Convention of Amateur Astronomers March 25-28, 2016…