Innholdsfortegnelse for August/September 2018 i Australian Sky & Telescope

DO YOU REMEMBER when you first looked through a telescope? Was it when you were young or much later as an adult? And do you remember the feeling you had when seeing real objects floating in space for the first time? Not pictures on a page or a screen, and not science fiction, but the real thing. It’s a fabulous feeling to suddenly realise that there really is a whole universe out there, just waiting for you to explore it by proxy through some clever optical wizardry. Most astronomy enthusiasts, although not all, go on to buy (or in the old days, build) a telescope of their own. What was your first scope? Was it the archetypal department store 60-mm refractor that boasted 500 million times magnification? Perhaps it was…

NEW SIMULATIONS SUGGEST that galaxies like the Milky Way could be home to a dozen big black holes. A gigantic black hole sits at the centre of the Milky Way and most other large galaxies. But when galaxies merge, their central black holes can find themselves with an eviction notice. Astronomers have increasingly realised that evicted black holes only migrate to the new galaxy’s core in a small fraction of mergers. The problem is especially acute when one of the galaxies is much smaller than the other. By implication, then, the outskirts of big galaxies should play host to a large number of supermassive black holes. To understand wha this means for galaxies like the Milky Way, Michael Tremmel (Yale University) and colleagues used the Romulus set of simulations, which…

Sixty-some years ago, Sputnik became Earth’s first artificial satellite. But it wasn’t the only thing launched that day — the main rocket stage of the launch vehicle also ended up in orbit. There are now more than 9,000 tonnes in orbit around Earth, and 80% of that is orbital debris — ‘space junk’. Space is famously big, so you might think that even tens of thousands of orbiting objects would have plenty of room to themselves. Indeed, the average distance between debris at any moment is hundreds of kilometres. But each of those objects is flying around Earth at swift speeds: 28,000 km/hr in the lowest, fastest orbits. They sweep through so much space in the course of a short time that the occasional cosmic collision is not only likely…

Space heritage is the evidence of human exploration of space in the 20th and 21st centuries. It comprises objects and places on the surface of the Earth, such as launch sites and tracking stations; satellites and space junk in Earth orbit; planetary landing sites; and deep space probes throughout the Solar System. It represents a distinct social and technological phase of human cultural evolution. By far the largest off-earth component of this heritage is located in Earth orbit. Since the launch of Sputnik 1 in 1957, Earth orbit has become filled with debris — more than 23,000 pieces larger than 10 cm, and millions of fragments below this size. Due to the damaging effects of high-speed collisions between bits of space junk, the increasing amount of debris is starting to…

Quality finder, easy to adjust to align with the main scope Sharp image from edge to edge when using different eyepieces Eyepiece at a comfortable height for viewing while standing or seated Smooth focuser with ‘precise’ feel (especially important for high-magnification viewing) Scope stops shaking quickly after being touched (check while using a high-magnification eyepiece) Mount moves smoothly on both axes, allowing fine control; little or no jerking or backlash Scope and mount can be carried and set up easily Pieces easy to disassemble for transport and storage, easy to reassemble in the dark Able to return it if it repeatedly fails to produce sharp images once you get it home…

This time of year is a relatively quiet period for meteor showers in the Southern Hemisphere. Our northern friends are getting ready to be thrilled by the Perseids, but unfortunately we barely get to see them from our latitudes as the radiant is at declination +58°. Not to worry — beginning in September we will have the Southern Taurids to look forward to, which, although always low in numbers, do put on a good show in September and October. This year the shower will be active from September 10 to November 20, peaking on the morning of October 10. The Southern Taurids are groups of meteoroids originating from comet 2P/ Encke. The meteors can be any colour, with many of them leaving trains that last for minutes. The shower is…

This column is usually concerned with the visual observation variable stars, and the contribution amateur observers can make to science. But this month let’s go further afield. Every two years on the Easter weekend, the National Australian Convention of Amateur Astronomers, or NACAA (pronounced ‘Nakka’) is held, hosted by a different astronomical association each time. The idea is for amateurs to meet and share ideas and techniques (and gossip) with other amateurs over coffee, a beer and good food. It’s a unique opportunity to make new acquaintances and meet people we otherwise would only get to know online. Of course, more formal presentations and functions are scheduled over the weekend, and some professional astronomers participate also. This year it was the turn of the Ballaarat Astronomical Association in collaboration with…

OBSERVING GUIDE Willmann-Bell has released The Night Sky Observer’s Guide Volume 4: The Glories of the Milky Way to -54° by George Robert Kepple (US$34.95). This fourth volume of the series describes the appearance of more than 1,800 deep sky objects in the Milky Way as seen through 15-to 47-cm telescopes, including more than 1,000 targets not included in previous volumes. The book begins with a primer on the types of objects to be observed, as well as equipment and observing strategies. The following 23 chapters focus on each individual constellation of interest within the plane of the Milky Way. Nearly 1,000 black-and-white photographs and sketches complement the author’s detailed descriptions. Hardbound, 21.5 by 28 cm with 500 pages, ISBN 978-1-942675-06-8. willbell.com ULTIMATE ASTROGRAPH Celestron has announced its flagship astrograph,…

Amateur astronomer Leos Ondra discovered a variable star, NSV 24959, within the nebulous borders of M27 in 1991. Because it’s located farther away than M27, we view the Goldilocks Variable through the nebulosity. NSV 24959 has a magnitude range of 15.2 to 17.1 and is apparently a Mira-type variable with a period of approximately 213 days. And much like the variable stars of Messier 5, the NSV 24959 variable is another reason to check in on the Dumbbell Nebula more often. I haven’t looked for this star yet, and it doesn’t show up in any of my sketches by accident. A bit unlucky perhaps, but I’ll certainly be keeping a careful eye out for it from now on. For more information, see: messier.seds.org/xtra/leos/gl.html…

IN HIS YOUTH, Steve Hosein spent many evenings looking up at the stars. In later years, he saw the sky from a Moroccan desert, the Peruvian Andes and at sea near Tasmania. He was used to crisp stars even before he began using a telescope, so it’s no surprise that high contrast and quality were important when he began to build his own scope. But other than using excellent optics, what can a person do to improve the view through a standard Dobsonian? Turns out, there’s quite a bit. Cooling the primary mirror is the first thing. A mirror that’s warmer than the air around it will warp, and air currents will form in the light path, leading to even more distortion. In an enclosed tube, primary mirrors spend most…

HOW TO SUBMIT YOUR IMAGES Images should be sent electronically and in high-resolution (up to 10MB per email) to contributions@skyandtelescope.com.au. Please provide full details for each image, eg. date and time taken; telescope and/or lens; mount; imaging equipment type and model; filter (if used); exposure or integration time; and any software processing employed. If your image is published in this Gallery, you'll receive a 3-issue digital subscription or renewal to the magazine.…

NASA’S INSIGHT MARS LANDER launched aboard an Atlas V rocket on May 5, rising through the predawn fog from the Vandenberg Air Force Base in California. The spacecraft’s name stands for Interior Exploration Using Seismic Investigations, Geodesy, and Heat Transport. Prime contractor Lockheed Martin Space based the spacecraft design on the Phoenix lander, which touched down near the Martian north pole in 2008. Insight should arrive at Mars on November 26 after an interplanetary cruise of nearly 500 million km. The spacecraft will make a direct descent to the planet’s surface. About 6 minutes after entering the Martian atmosphere, Insight will use — as Phoenix did — a combination of aerodynamic drag, parachutes and radar-triggered thrusters. However, compared to Phoenix, Insight is more massive (358 kg), arrives at higher velocity…

CubeSats launch with Insight Along for the ride with the Mars-bound Insight spacecraft are twin microsatellites called Mars Cube One (MARCO) A and B, the first CubeSats to visit interplanetary space. Each spacecraft comes equipped with solar panels, cold-gas thrusters, an X-band antenna and an ultra high-frequency receiver. Both spacecraft also have star trackers and wide- and narrow-field cameras. The satellites deployed successfully from spring-loaded launchers located on the Centaur upper stage and phoned home shortly after their release, indicating that their solar panels and communications antennae were functioning. The duo will fly past the Red Planet in November and attempt to relay data from the lander’s descent to the Martian surface, transmitting data from Insight to Earth at 8 kilobits per second. While the success of the Insight mission…

One aspect of the space junk problem that tends to get media attention is what happens when larger chunks re-enter Earth’s atmosphere. While a lot of the debris pieces are made of aluminium, which melts during re-entry, some denser and hardier parts survive the fiery descent and reach Earth’s surface. In the 60-some years since Sputnik, though, no one has been hurt, and there has been no serious damage from things falling from the sky. In 1962 the service module of Sputnik 4, the prototype Vostok spaceship, re-entered over the US — a piece of it was found in the middle of a street in Manitowoc, Wisconsin, but there wasn’t even a crater. The most notorious re-entry was also the biggest ever — the 77-tonne Skylab space station, which broke…

AUGUST 4 Uranus 5° north of Moon 7 Aldebaran 1.1° south of Moon 9 Mercury in inferior conjunction 11 Lunar eclipse 15 Venus 6° south of Moon 16 Moon 8° north of Spica 17 Jupiter 5° south of Moon 18 Venus greatest elong. east (46°) 18 Mercury stationary 19 Moon 9° north of Antares 21 Saturn 2° south of Moon 24 Mars 7° south of Moon 27 Mercury greatest elong. west (18°) 28 Mars stationary SEPTEMBER 2 Venus 1.4° south of Spica 3 Aldebaran 1.2° south of Moon 6 Mercury 1.0° north of Regulus 6 Saturn stationary 8 Moon 1.8° north of Regulus 13 Venus 10° south of Moon 18 Saturn 2° south of Moon 20 Mars 5° south of Moon 21 Mercury in superior conjunction 21 Venus greatest illuminated…

JUPITER, STILL IN LIBRA, appears high in the west all month. Near the middle of August, about 6½ hours separates sunset and Jupiter-set, with the gap slowly growing smaller as the evenings pass. Jupiter reaches east quadrature (90° east of the Sun) on August 6. This is a good time to shadow watch as Jupiter’s moons dance around the planet. Any telescope shows the four Galilean moons, and binoculars usually show at least two or three. Here are the times, in Universal Time, when the Great Red Spot should cross Jupiter’s central meridian. The dates, also in UT, are in bold. Aug. 1, 0:54, 10:49, 20:45; 2, 6:41, 16:37; 3, 2:33, 12:28, 22:24; 4, 8:20, 18:16; 5, 4:11, 14:07; 6, 0:03, 9:59, 19:54; 7, 5:50, 15:46; 8, 1:42, 11:38, 21:33;…

M27 has everything going for it. It’s a large, bright planetary nebula with a striking and subtly detailed shape. It’s well placed in the northern sky (about altitude 33° from Sydney) during the middle months of the year. It has a famous nickname that captures the essence of its shape. It’s even easy to find, especially if you triangulate its position using Gamma (γ) and Delta (δ) Sagittae. Almost universally referred to as the Dumbbell Nebula, the brightest parts of M27 really do look like a handheld workout weight. But it often looks even more like an apple core or an hourglass. John Herschel coined the dumbbell name and suggested the hourglass comparison in 1827. The resemblance to an apple core, which is a more modern nickname, is just as…

Helicopter to fly with Mars 2020 rover NASA has announced that a small, autonomous helicopter, named Mars Helicopter Scout, will make the journey to the Red Planet with the Mars 2020 rover. It may become the first mission to fly on another planet. Tucked away under the rover during descent, the helicopter will be deposited on the Martian surface shortly after landing. Weighing in at 1.8 kg, the baseball-size helicopter will whip its rotor blades at 3,000 rpm (10 times the rate of a helicopter on Earth) to create lift in the tenuous Martian atmosphere. As a technology demonstrator, the helicopter won’t carry science instruments, but it will have two cameras that could prove valuable in mapping terrain. Funded for US$23 million early this year, the helicopter is expected to…

AT LEAST 14 GALAXIES congregating just 1.4 billion years after the Big Bang might have become one of the most massive structures in the universe — if we could observe it to the present day. Each galaxy in this protocluster is alight with stars forming 50 to 1,000 times more quickly than the Milky Way; the complex as a whole has the mass of 10 trillion Suns. The fact that these galaxies came together in such a massive structure so early on challenges our ideas of how clusters form. Clusters, the largest gravitationally bound structures in the universe, contain hundreds or thousands of galaxies tethered together by their massive halos of dark matter. As galaxies are coming together, such a group is called a protocluster, and its future isn’t guaranteed…

STEPHEN HAWKING’S LAST cosmology paper, published posthumously with Thomas Hertog (KU Leuven, Belgium) in the Journal of High Energy Physics, might solve the cosmological problem of eternal inflation. A lot of evidence suggests that, just a tiny fraction of a second after the Big Bang, the infant universe experienced inflation, a brief, fantastic growth spurt. Our pocket of space — what we call the observable universe — experienced a quantum fluctuation and spontaneously exited inflation. But according to most theories, inflation wouldn’t have stopped everywhere at once. Beyond what we can observe, most of space will keep stretching at an exponential rate forever. Eternal inflation implies that our cosmos is one of an infinite variety of pocket universes, known as the multiverse. Each one follows an infinite variety of physical…

THE WINNERS OF THE ASTRONOMICAL SOCIETY of NSW’s annual Astroimaging Competition are announced each year during the South Pacific Star Party at the Society’s rural dark sky property, Wiruna. And this year, once again, the work produced by some of Australia’s best astrophotographers is nothing short of spectacular. As a supporter of the Competition and Star Party, Australian Sky & Telescope is proud to publish the winning images from this year’s deep sky and open categories, and we extend our congratulations to the photographers.…

You’re ready to buy your first telescope — Woohoo! You probably have lots and lots of questions. How much money should you spend? What model should you get? Reflector, refractor or catadioptric? Equatorial or alt-az mount? Do you need a computerised telescope? And what about astrophotography and imaging? Hold on — one step at a time! Hopefully you’ve already done some basic homework. In addition to reading reviews, both in print and on the internet, it helps to have some good reference books, including a star atlas. And you’ll want to try a few scopes before committing to one. Local astronomy clubs often hold public ‘star parties’ where visitors can look through a variety of telescopes, often for free. Buying a telescope isn’t that different from buying a computer or…

The innermost planet, Mercury (11" diameter and mag. 2.9 on Aug 1; 4.8" and –1.0 by Sep 30), is essentially out of view during August and September, reaching inferior conjunction (between the Earth and the Sun) on August 9, after which it hugs the eastern dawn horizon for the rest of the month, only 5 or 6 degrees in altitude. September is no better, with the planet swinging around to the other side of the Sun (superior conjunction) on the 21st and pretty much lost to view on the western twilight horizon. The tiny world will be easier to find in the western twilight in October. Venus (30", –4.6 on Sep 1) is a better bet, shining brightly in the western sky from early twilight until about 9:00pm. Currently in…

These subtle shells have nothing to do with planets and everything to do with the death throes of Sun-like stars. The misnomer originated with Charles Messier’s description of M57 and was later reinforced by both William and John Herschel. Some of these nebulae really did look like ghostly versions of Jupiter or Uranus through their telescopes — small, round and evenly illuminated. So the term ‘planetary nebula’ made sense from that standpoint. Even so, many of them, like M27, don’t resemble planets at all. We now know planetary nebulae are the glowing remains of a red giant star that were expelled by instabilities created inside the star as its fusion reactions sputtered to a halt. During this process, the red giant contracts into a tiny white dwarf star. Once the…

If you’re interested in the real guts of binoculars, how prisms, focusers, coatings, and the rest work together, don’t hestitate to get this book. Even if you’re a more casual binocular user, you’ll find much of value here. Binoculars: Fallacy & Fact isn’t like other binocular books. It seems to have been directly downloaded from the brain of the author, William J. ‘Bill’ Cook, Chief Opticalman, US Navy (retired). It’s idiosyncratic and informal, but also authoritative on many technical aspects of binoculars, and indispensable in describing techniques that aren’t otherwise in print. The book is self-published, and it shows. Physically it’s fine, with an attractive soft cover, good paper and print quality, and over 100 black-and-white photos and diagrams. The self-publication becomes more evident in the organisation and writing. The…