Innholdsfortegnelse for November - December 2022 i Australian Sky & Telescope

COMPETITION Now in its 14th year, the Royal Observatory Greenwich's Astronomy Photographer of the Year competition attracts contributions from astrophotographers, young and old, from all around the world. The images they produce are always amazing, and this year's entries are certainly no exception. We've showcased just a few of them on these pages — you can see the rest of them online at rmg.co.uk.…

PLANETARY EVENT IN MANY WAYS, robotic exploration of Mars has relegated amateur astronomers to the status of telescopic tourists. NASA's Mars Reconnaissance Orbiter has mapped nearly the entire surface of the Red Planet at a resolution of 6 metres or better. Five landers and six rovers have sifted Martian soil and sniffed Martian air. In the span of a single generation during the closing years of the 20th century, “the very character of the scientific questions changed as the planets went from being astronomical objects to geological objects,” notes William K. Hartmann of the University of Arizona's Planetary Science Institute. Yet a few mysteries from the era of earthbound planetary exploration still linger. Prominent among them are Martian ‘flares’ — gleaming points of light that suddenly appear and persist for…

COSMIC RELIEF Astronauts to Venus? It sounds like a joke, delusion or cruel punishment. Yet recently I spent two days at Caltech in a workshop titled ‘Venus Science Enabled by Human Proximity’. Why would bright and apparently sane people gather to discuss such an outlandish thing? We all know that Venus is an oven, about the last place you'd want to send people. Yet it's the closest planet to Earth, rich with mystery and untapped, priceless knowledge. There are important lessons that we'll never learn about our home planet, and therefore about ourselves, until we deeply explore this neighbouring world. These lessons include the origin and fate of Earth and the uniqueness of our biosphere, as well as the mechanics of climate change on Earth-size, geologically active worlds. We need…

COMETS More than five years after its discovery, C/2017 K2 (PANSTARRS) will finally reach perihelion on December 19 at a distance of nearly 1.8 AU from the Sun. The progress of this comet has been of great interest to professional astronomers, as it has provided a rare opportunity to observe the evolution of activity on a long-period comet as it moves from the region of the outer planets — where water ice is as stable as rock and activity is driven by very volatile chemicals — into a region where the sublimation of water ice begins to take over as the principal cause of activity. For observers, C/2017 K2 will begin November in Norma, moving to Ara in the middle of the month and into Pavo about one month later.…

NIGHT LIFE There's a brand new public astronomy event on the calendar in Victoria, the Sea Lake Astro Fest, an initiative of the Astronomical Society of Victoria. The event will be held from October 29 to 31, 2022, at Lake Tyrell in north-western Victoria, a location famous for its salt lake — the largest in the state. It has become a magnet for astrophotographers keen to take spectacular nightscape shots of the night skies reflected in the water. The Sea Lake Astro Fest will feature a range of activities to suit every taste, from the general public to experienced amateur astronomers. At the time of writing, the three public viewing sessions had already been booked out, but there are plenty of places available for the other activities: • ‘Science in…

A LOT CAN CHANGE in four decades. I got my first telescope in 1980 at age 12. My Edmund Scientific 75mm reflector wasn't much — just a red tube, two mirrors, an eyepiece and a wooden tripod. But I was blown away when I pointed that tube at Saturn and saw its rings floating so vividly against the black backdrop of space. When I mentioned this weeks later at a family party, one of my uncles confessed to me, “I haven't seen Saturn in 20 years!” I was stunned, not only to learn he was an amateur astronomer, but also to imagine that anyone would let two decades pass without viewing those fantastic rings. I silently vowed not to let that happen to me. At 13, I acquired a used…

NEWS NOTES JUST LIKE A PLAIN-LOOKING pupa becomes a beautiful butterfly, a rogue moon of Saturn might have turned into the planet's spectacular ring system. Jack Wisdom (MIT) and his colleagues propose that tidal forces tore apart the unfortunate moon a mere 150 million years ago or so. The scenario could also explain Saturn's axial tilt, and the somewhat elongated orbit of the planet's largest moon, Titan. Wisdom and his collaborators note that Saturn's precession — the slow wobble of its spin axis — has almost, but not quite the same period as the precession of the orbit of Neptune. The researchers thus suggest there was once a true spin-orbit resonance between the two planets. The relatively rapid drifting-away of Titan (which currently spirals outward at about 11 cm per…

ASTRONOMERS HAVE FOUND a dormant stellar-mass black hole circling a massive blue star in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way. The black hole seems to have formed without throwing off an accompanying supernova, opening the door to our understanding of direct collapse scenarios. A team led by Tomer Shenar (University of Amsterdam, The Netherlands) trawled through almost 1,000 stars in the LMC's Tarantula Nebula in search of dormant black holes. They found exactly one, known as VFTS 243, by analysing six years of non-consecutive data from the Very Large Telescope. Showing that a binary system contains a dormant black hole is notoriously difficult, because the system could contain another dim object (or two) with equivalent mass. In fact, the team behind this discovery is…

DISCOVERIES In exploring the early history of astronomy — before the explosion of knowledge that came through Copernicus and Galileo, Kepler and Newton (and many others) — we must not overlook India. While Europe was in the ‘dark ages,’ a thousand years or more ago, Indian astronomy was flourishing. Its origins dated back at least further thousand years. Astronomy was then much entwined with religion; observations of the heavens and their movements were needed to set the best dates for important rituals and festivals. Ancient Indian astronomy reached a peak with Aryabhata, born in 476 CE, about the time the barbarians were ravaging the remains of the Roman Empire in Europe. Details of his life are sketchy and contested but he was associated with a school of astronomy and mathematics…

CLIMBING THE LADDER COWS CAN'T JUMP OVER THE MOON, no one has ever touched a star, and according to the opening crawl of Star Wars, galaxies are “far, far away”. But if tape measures don't work in the wider universe, how do astronomers gauge cosmic distances? How did we endow the night sky with a third dimension? And, given that space is expanding, what does the concept of distance mean anyway? Many people struggle with these ideas. Separations of thousands or millions of light-years quickly lose their meaning when the method behind the measurement eludes you. So we've decided to tackle the matter head-on, starting in the Solar System and expanding out to the farthest reaches of the cosmos. Buckle up for our crash course in cosmic surveying. Step 1.…

STAY PARTY I've always thought that the Greek mathematician Claudius Ptolemy came as close as anyone ever has to capturing in words, the feeling we all have when the Milky Way and the majesty it represents comes to mind. The quote is archaic, but everyone will surely recognise his intent: “I know that I am mortal and the creature of a day; but when I search out the massed wheeling circles of the stars, my feet no longer touch the earth, but, side by side with Zeus himself, I take my fill of ambrosia, the food of the gods.” Indeed as the Sun descended below the horizon each evening of the 2022 Queensland Astrofest (held July 22-31), there came that frisson that all astronomers know so well — the sense…

This year will end with a bit of a bang as we experience two planetary oppositions and a total lunar eclipse… just in time for the warmer summer weather. Mercury (mag. -0.9, dia. 4.7″, Nov. 20) begins November out of sight in the glare of the Sun (superior conjunction on the 9th) as it shifts from our morning eastern sky to the western evening sky. You'll be able to spot the planet low on the western horizon after sunset at the end of November, and watch as it climbs higher during December (greatest solar elongation of 20° on December 22). During this period it will remain close to Venus, with the two planets appearing within two degrees of each other from December 28 to 30. Out of view in the…

November's total lunar eclipse will be the first eclipse of any kind that stargazers in our part of the world will experience this year, with the event to be visible across Australia, New Zealand and the Pacific, as well as Asia and much of the Americas, The evening hours of November 8 will find the Moon crossing the northern half of Earth's umbra. The partial phase will begin at 9:09 UT, though attentive observers will notice the much gentler bite of the penumbra across the eastern half of the Moon well before this. Totality will get underway at 10:16 UT and will last 86 minutes until the partial phase resumes at 11:42 UT. (Add the correct number of hours to determine the time in your local time, depending upon whether…

AS&T TEST REPORT Evolux 82ED Australian RRP: $1.599.99 skywatcheraustralia.com.au What we like Optics with low chromatic aberration Excellent corner sharpness with optional reducer/corrector Extra-long dew shield What we don't like Defective focuser Crude camera rotation mechanism I THINK IT'S FAIR to say that telescopes from Synta's Sky-Watcher brand have helped to democratise the use of apochromatic, or colour-free, refractors. Compared to the lofty price of US$400 per centimetre (or much more) typical of prestige brands, Sky-Watcher's affordable offerings made apos accessible to more buyers. So, when Sky-Watcher introduces a new series of apos, that's news worth noting. The Evolux series For several years, Sky-Watcher has offered two lines of apo refractors: the entry-level EvoStar series, which features lower-cost doublet lenses, and the premium Esprit series with triplet lenses employing Ohara…

WHEN NASA'S OSIRIS-REX took a sample from the asteroid 101955 Bennu on October 20, 2020, it revealed that this little world is more rubble pile than solid rock. New analyses in the journals Science and Science Advances show that when the probe touched down, it punched right through the surface. If the spacecraft hadn't lifted itself back out a few seconds later, the asteroid would have engulfed it. On sampling day, a 3.35-metre-long articulated arm attached to the probe unfolded to deploy an aluminium collection head; together, these pieces make up the Touch and Go Sample Acquisition Mechanism (TAGSAM). The probe approached the surface at a slow 10 cm/s. The plan was then for the TAGSAM head to touch the surface and stay there for 5 seconds while a jet…

JUST 700 MILLION YEARS after the Big Bang, we already see supermassive black holes with the heft of 1 billion Suns. Now, a team of astronomers is using computer simulations to demonstrate the formation of these dark behemoths. In their scenario, massive clouds of pristine gas collapse directly into black holes in the early universe. The calculations for such massive implosions are delicate, though. What's to prevent the gas cloud from fragmenting and forming smaller stars, as the ones in the modern universe are wont to do? Previously, astronomers have suggested the ultraviolet emission of nearby newborn stars might have heated the gas, keeping it too warm to fragment. But such specific requirements would have made the process rare. Now, Muhammad Latif (United Arab Emirates University), Daniel Whalen (University of…

SPACE TELESCOPE The James Webb Space Telescope has zoomed in on the Orion Nebula as one of its first targets, sharing with us a clearer picture of the giant stellar nursery. Even at 1,350 light-years away, the nebula is visible to our unaided eyes as a pale smear next to the threestarred belt of Orion. It has been the target of many an amateur astronomer and astrophotographer, as well as the Hubble and Spitzer Space Telescopes. But Webb has provided the clearest and most unique picture to date, its NearInfrared Camera peering through the dust that enshrouds the infant stars. Yet to many amateur astronomers, the image was at first is difficult to place. That's because most of the young, massive Trapezium stars — the cluster that's central to most…

TOASTY JUPITERS EXOPLANETS HAVE TURNED our textbook theory for planet formation on its head. When astronomers first imagined planets around other stars, we envisioned that every star's entourage would look similar to our own Solar System: planets circling their star in a flat disk, with rocky planets near the star and gas giants far out. This setup, we had inferred, arose due to how planets form. Each planetary system begins as a spinning cloud of gas and dust that collapses into a disk. In the vast expanses of the outer, cold region of the disk, far from the young star, there's more solid material (including ice) available to build the core. Planetary cores grow large and blanket themselves in material from the surrounding disk to become gas giants. Closer to…

Is there an amateur astronomer who hasn't enjoyed looking at Rupes Recta? Commonly known as the Straight Wall, as the Latin name implies, the 110km-long feature is relatively straight, and its shadow reveals its nature as a wall, cleft or scarp. Even small telescopes can show the Straight Wall's shadow gradually diminishing as the Sun rises over the feature. From full Moon on, the Wall reflects the Sun's rays and appears as a bright line etched on the lunar surface. Measurements reveal that the eastern side is about 400 metres higher than the mare-covered western side. Although correctly interpreted as a fault scarp for many decades, the Straight Wall escaped modern analysis until 2015, when Amanda Nahm (then at the Lunar and Planetary Institute) and Richard A, Schultz (formerly of…

IN PROFILE In 2022 Paul ‘Starman’ Curnow celebrates his 30th year of teaching astronomy at the Adelaide Planetarium, making him South Australia's longest continuously serving ‘planetarian’. What got you into astronomy? As a small child I always had a fascination for anything to do with the cosmos. I have fond memories of sitting on the front lawn with my mother during summer evenings and looking at the sky. Although she didn't know the constellations well, she was able to point out some basics such as Crux, the Pleiades and the asterism ‘The Saucepan’. I was fortunate to grow up during an exciting time in history. I remember humans landing on the Moon, and who wasn't addicted to ‘Lost In Space’ in the late 1960s as they attempted to head off…