Innholdsfortegnelse for August/September 2019 i Australian Sky & Telescope

Astronomy is sometimes thought as a study without any practical use. How can observing celestial objects, at distances from Earth so vast we cannot conceive them, assist human well-being and happiness? We can argue, of course, that that astronomy has given us an understanding of our place in the cosmos, in itself an immense stimulus to the human imagination and spirit. But we can go further. Until quite recently, astronomical observations were of vital practical importance, most crucially in timekeeping and navigation. Such sciences were vital for the ordering of society, and for making trade possible with distant lands, with all the economic and social consequences that follow. We can underline this by considering this month’s anniversary. On August 10, 1675, the King Charles II laid the foundation stone for…

In last issue’s column, we began a survey of colours visible in the winter night skies. That column focused on star colours. We continue now with the hues of winter’s nebulae and star clusters — with a bonus at the end. Extra colours in the brightest planetaries. An arc of bright planetary nebulae is visible from Lyra to Aquarius on late-winter and early-spring evenings. These glowing grave wreaths of stars are the Ring Nebula (M57) in Lyra, the Dumbbell Nebula (M27) in Vulpecula, the Saturn Nebula (NGC 7009) in Aquarius, and the Helix Nebula (NGC 7293) also in Aquarius. The Saturn Nebula displays the most intense characteristic colour of these nebulae: blue (or greenish-blue if the lenses of your eyes have become too yellowed by decades of exposure to the…

Australian observers will be treated to two lunar occultations of Saturn in the next couple of months, on the nights of August 12 and September 8/9. These follow the occultation that occurred on April 25 and will precede the last of four such occultations for the year, coming up on November 2 (but this one will be visible only from New Zealand). A lunar occultation occurs when the Moon, slowly trundling along in its orbit, passes in front of a background object such as a star, planet or minor planet. Think of it as a sort of mini eclipse. Some amateur astronomers dedicate themselves to recording the exact timings of the disappearance and/or reappearance of these object, with those timings being useful in refining our knowledge of the Moon’s topography,…

WHEN IT COMES TO BIG transportable Dobsonian telescopes, the man to see is Peter Read. A music teacher by day and telescope builder by night, Read has been building premium custom-made Dobsonians in his workshop near the Victorian regional city of Shepparton since 2004. Today nearly 80 SDM telescopes (www.sdmtelescopes.com.au),with apertures up to 100 cm, can be found collecting photons all across Australia and as far afield as New Zealand, Canada, the USA and the UAE. With so many SDM telescopes in existence it was only a matter of time before an SDM star party was organised. And so it was in early April 2019 that eighteen telescopes and their proud owners, partners and friends, were invited to Allan Wade’s rural property near Coolah, NSW, for four days and three…

IT’S COMMON KNOWLEDGE in the ATM world that a reflecting binocular telescope requires six mirrors. You need the primaries to gather light and bring it to a focus, you need secondaries to bounce that light off to the side, and you need tertiaries to make the two light cones parallel again and aim them into your eyes. But there is a way to make a binocular scope with just four mirrors, and Frank Szczepanski has become a master at it. The idea has been around a while but for some reason it has never really caught on. It should have, though, because the design is simplicity itself: Simply lay two Newtonian scopes side by side and offset them both horizontally and vertically so the light path of one crosses through…

Carol Redford is co-chair of Astronomy WA, director of the Australasian Dark Sky Alliance, a member of the International Dark-Sky Association and a Dark Sky Ambassador with the International Astronomical Union’s ‘Dark Skies for All’ project. What got you into astronomy? My stargazing life began when I co-owned and operated the public observatory near Gingin in WA with good friend, Donna Vanzetti. I hadn’t been in contact with science since physics and chemistry in high school, so I’m really an accidental stargazer. After we sold that business, I founded Stargazers Club WA and more recently Astrotourism WA. I often think my physics teacher would be very proud of my role in the astronomy science community, considering I only scraped through with a pass! What was your first telescope set-up? A…

THE DUMBBELL NEBULA, also known as Messier 27 and NGC 6853, is one of my favourite nebulae, and over the years I’ve taken many pictures of it. I like to joke to my friends that it’s named after me — the dumbbell. Last October, I invited my first-year uni astronomy class to my home to show them how to do some astrophotography. Eight students came. We snapped images of stars and other objects before I suggested we take a sequence of pictures of M27. They agreed, and over the next few hours my telescope and camera did just that while my students and I enjoyed tea and cake inside and talked astronomy. The resulting photo came out pretty nicely — almost as nicely as one I’d taken two years earlier…

Each year, Australian Sky & Telescope is proud to publish the winning and placing entries in the deep sky and open categories of the Astronomical Society of NSW’s annual Astroimaging Competition. As with past years, this year’s spread of photos is quite amazing and a vivid testament to the skill of the photographers. Great astrophotography doesn’t just happen — it often takes years of patient learning and experimentation to reach the standard you can see on these pages. So we’re sure you’ll join with us in congratulating all the photographers on their achievement. PHOTOGRAPHER: Ted Dobosz CATEGORY: Open PLACING: 3rd SUBJECT: Demonax crater DETAILS: Celestron C11, 3x Barlow, Basler Ace aca1920-155um camera, total of 800 frames from 60,000 taken (10 milliseconds each) PHOTOGRAPHER: Brad le Brocque CATEGORY: Open PLACING: 1st…

IT’S HARD TO IMAGINE LIFE EXISTING in an environment fundamentally different from that of Earth, a planet rich in vegetation and oceans orbiting a bright, yellow star. Indeed, for decades astronomers focused on Sun-like stars when hunting for habitable worlds, a decision that made logical sense for a number of reasons. Such stars have lifetimes of roughly 10 billion years, providing ample time for life to emerge if it follows the pattern it did on Earth. And Sun-like stars don’t pose the hazardous threats that other stars might when it comes to flares and magnetic activity, instead living relatively quiet lives. Above all of the reasons to pursue life around stars like the Sun, though, is one single fact that cannot be overvalued: The only known example of a habitable…

When you observe the Moon, do you ever wonder how old the crater you’re looking at is? Wondering is about all you could do for most craters, with the exception of a handful that were dated by studying samples brought back during the Apollo missions that had been shocked or melted during impact. But the formation date of the vast majority of craters was almost entirely unknown… until now. Sara Mazrouei, her advisor Rebecca Ghent of the University of Toronto, and their colleagues have developed an ingenious new technique for estimating the ages of lunar craters based upon the rockiness of their ejecta. When an impact excavates a new crater, large boulders are thrown out around its rim. The Diviner Lunar Radiometer Experiment infrared thermal sensor, onboard NASA’s Lunar Reconnaissance…

Perhaps the initial thing in the night sky people look at with their first telescope is the Moon. After all, it’s the brightest object in the sky, and doesn’t require any special equipment in order to see detail. In fact, no optical aid at all is necessary to see the dark lunar maria. The Moon can be seen from virtually any location on Earth and is completely impervious to light pollution. As such, our satellite is possibly the most tempting target for many amateurs to begin their journey into astrophotography. Whether you’re just starting out shooting the Moon or are considering some high-resolution close-ups, here are some tips to help you come away with pleasing shots. Without a scope The Moon is one of the most accessible objects you can…

A LOT HAS CHANGED during the 50 years I’ve been observing the night sky. Much of that change has been in the equipment we use to view it with. Typical amateur telescopes are bigger and undeniably better, mounts are more precise and modern eyepiece designs make the older ones look like antiquated magnifying glasses. For the amateur interested in viewing nebulae, however, light-pollution-reduction (LPR) filters are the innovation that’s perhaps brought the most profound change. For observers under urban and suburban skies, one of these filters can make the difference between seeing many objects and not seeing anything at all. A standard for me has been the filters from long-time accessory maker Lumicon (now owned by Optical Structures Incorporated). Recently, the company announced a ‘new and improved Generation 3’ oxygen…

NARROW VIEW Dave Moulton The Carina Nebula, seen here captured through narrowband filters, rivals the Orion Nebula for grandeur and complexity. For this shot, Dave used a Meade ED80 scope, QSI 583wsg camera and 4.5 hours integration. DARK WOLF Brendan Mitchell SL 17 — known informally as the Wolf nebula for obvious reasons — is a dark nebula located in Scorpius. For this shot taken under the dark skies of Karijini National Park, WA, Brendan used a Sky-Watcher Quattro 250P Imaging Newtonian, QHY 5L-II M camera and FLI Research grade LRGB filters. Total integration time was 15.9 hours. FLARE & STARS Domenic Lucarelli Purely by chance, Domenic caught an Iridium satellite flare when snapping this quick shot of the Magellanic Clouds. He used a tripod-mounted Canon EOS 70D camera and…

ASTRONOMERS OBSERVING NEARBY interstellar space have finally detected helium hydride (HeH+ ), the first molecule to form in the early universe. Rolf Güsten (Max Planck Institute for Radio Astronomy, Germany) and colleagues report the find in the scientific journal Nature. The early universe contained mostly hydrogen and helium, so it’s perhaps unsurprising that its first molecule would be helium hydride. But of all the elements, helium requires the most energy to remove an electron — it’s no easy feat for it to combine with another atom. Indeed, the ion didn’t survive long even in the unique conditions of the early universe, but it played a brief but important role. Its destruction gave rise to molecular hydrogen (H2 ), which eventually permeated galaxies and star-forming reservoirs. The existence of HeH+ is…

IT WAS A “GIANT LEAP FOR MANKIND,” and it was taken at 12:56pm on July 21, 1969, Australian Eastern Standard Time. Six hundred million people, one sixth of the global population at the time, watched the Apollo 11 moonwalk live on television. What most people didn’t realise was that those TV pictures were being received in Australia as a result of Australian expertise. What were the circumstances that brought about this amazing event and why was Australia involved in the first place? The story begins in 1961. The Cold War The Apollo 11 lunar landing was the culmination of an incredible decade of frenetic activity in the United States. It was conceived as a Cold War geopolitical exercise by a newly inaugurated, young US President, wanting to demonstrate the superiority…

I love the Moon. There’s nothing like it in the sky. It’s totally alien and yet completely accessible. No spacecraft needed. No squinting through a telescope to eke out a dim feature. No going online to look at the latest flyby photos. Just look up! It’s big, bright, and there to enjoy and inspire in so many ways — moonlit walks, moonrises, eye-popping pairings with bright stars and planets, and in wondrous detail through a telescope. No other body offers such easy access to the cosmos better than the one closest to home. Even for the casual observer the Moon is beautiful and approachable. I can’t count the number of times someone has come to up me, cellphone in hand, excited to share their latest photos of the moonrise. Sitting…

The close of winter and early spring does not look like being a promising period with respect to bright comets. But, as I mentioned in the previous issue, the distant object C/2017 T2 (PANSTARRS) will drift slowly through Taurus throughout this time and, even on initial conservative predictions, may become visually accessible to those with larger telescopes by early spring. Indeed, if the reported brightness of this object just before vanishing into twilight in autumn represents anything more than a brief outburst, the comet may be significantly brighter than the early predictions. Observers with large instruments and good skies might like to try for this comet as soon as it reaches observable altitude. It may surprise us! Even if August and September do not, this year, bring forth anything spectacular,…

The region of the sky in and around Ophiuchus fascinated William Herschel; E. E. Barnard repeatedly returned to it in an attempt to understand the structure of the Milky Way. If you spend a little time with the constellation, then you’ll begin to understand some of the historical misunderstandings that arose here. Observing this region, Herschel reacted with shock as he swept past such objects as the globular star clusters M80 and M4 only to enter what would become known as the dark nebula Barnard 42 and the bright nebulae IC 4603 and IC 4604. He proclaimed that he’d discovered a “hole” in the sky without a star to be seen. William’s sister, Caroline, wrote to her nephew, John, warning him to take care when observing this region — her…

Protection of the eyes’ dark adaptation is vital to visual astronomers. They share this need with aviators, mariners and military and security personnel. Even nocturnal pedestrians benefit from not being ‘night blind’. Yet while we have a decent understanding of how the eye recovers after it’s exposed to bright light, few researchers have investigated how exposure to faint light sources impairs vision, or which colour least interferes with dark adaptation at low levels. Red has traditionally been the lighting colour of choice for visual astronomers, both for navigating safely around their environment and for reading charts. But there are no data to confirm that red is in fact the most appropriate colour for this purpose. When asked, astronomers will often (and incorrectly) state that the retinal receptors we use in…

IN THE 1970S, scientists James Lovelock and Lynn Margulis proposed the Gaia hypothesis, which likens our biosphere to a self-regulating organism. In the decades since, the idea that biological evolution is inseparable from planetary processes became part of mainstream Earth-system science. Just as an individual living thing such as a sea slug can exhibit sophisticated internal self-regulation without needing abstract thought, our biosphere may help regulate the planet without any self-awareness. Yet sometimes I wonder. Through our influence on our planet’s history, cognitive processes have become, in a way, planetary processes. Humans are the first geological force to be aware of its own existence. But beyond this, could there actually be some emerging mind — and not just metaphorically — that is global in scale? Many have noted superficial ways…