Innholdsfortegnelse for January - February 2023 i Australian Sky & Telescope

SPECTRUM A YEAR AGO ON THIS PAGE, I wrote that I much prefer the summer stargazing season over that of winter, largely for sentimental reasons — it was summertime many moons ago when, as a teenager, I first got into observing the night sky. Of course, the warmer weather helps a lot too. Summer stargazing, for me, conjures images of open star clusters. I'm not entirely sure why, but to me they are the epitome of cosmic magnificence… particularly for casual, recreational observing with a pair of binoculars. Nebulae are wonderful, but the human eye is not great at discerning them in tremendous detail. Yes, a few look good through a telescope, but a lot of them remain fairly dull and pale. What about globular star clusters? Again, they're magnificent,…

The first image of our galaxy's central black hole gives us a peek at a bizarre object. ENTHRONED IN THE MILKY WAY'S HEART sits the cowardly lion of black holes. Known as Sagittarius A*, this object holds the equivalent mass of 4 million Suns squashed into a region less than 20 times as wide as our star. A diffuse veil of hot gas skirts the beast, fueling a glow only about 100 times brighter than the Sun — so feeble that, if it lay in another galaxy, it would probably be undetectable. Astronomers first detected Sgr A* (pronounced ‘sajay-star’) in 1974 as a ‘compact radio source,’ just as the realisation was dawning that big black holes might sit in most galaxies’ cores. Over the decades, observers tiptoed closer to its…

Player One Astronomy has announced an accessory cooling unit for its high-speed cameras. Retailing for US$49.00, the ACS (Active Cooling System) connects to the rear plate of certain Player One solar or planetary imaging cameras. The device has a heat sink and a magnetic levitation fan that together help to lower the temperature of the camera's sensor. This reduces the thermal noise generated in its solar cameras as well as some of the company's planetary cameras when used for deep sky images requiring long exposures. The device connects to the camera's housing with four M 2.5 x 40 screws that replace four on the rear of the housing. The ACS is powered through a 2.1-mm, 12-volt, 3-amp DC power port (power supply not included), and a dial adjusts the fan…

STELLAR FRONTIERS A WHITE DWARF is an extraordinary object. If you could stand on its surface and drop a pebble, the stone would smash into the star a split second later at thousands of kilometres per hour. The tiny star's immense surface gravity arises because the typical white dwarf packs 60% of the Sun's mass into a sphere that's only slightly larger than Earth. Its gravity, therefore, pulls that pebble down hard. Yet these extraordinary objects are common, making up 6% of the stellar population of the Milky Way. They represent the eventual fates of most stars, including our Sun, after they run out of fuel. Since white dwarfs abound, many shine nearby. The closest is just 8.6 light-years from Earth, orbiting brilliant Sirius in Canis Major. Designated Sirius B,…

I REMEMBER DREAMING about owning my first telescope and planning on what I'd look at when I got it and what each object would look like. When my parents finally bought one for me, I was ecstatic! It was a 114mm Newtonian reflector, which seemed even more impressive to me than the long, skinny refractors I'd favoured. But what was that weird mount it was on? I'd never considered the mount before, only the views I'd get through the scope. It took me a bit of time before I learned what an equatorial mount was and how to use it. Telescopes come on all kinds of mounts, with fancy names like German equatorial, centre-balanced, open fork, English yoke, and one that sounds rather intimidating but really is the most basic…

Wayne Orchiston, Peter Robertson, Woodruff T. Sullivan III Springer, 2022 281 pages, ISBN 978-3-319-91843-3 https://bit.ly/3DljrYc(free e-book) Also available in hardcover, €49.99 THAT AUSTRALIAN scientists have long been world leaders in radio astronomy is something of which many people in the community will be at least somewhat aware. Lots of people have seen the movie ‘The Dish,’ the story of the role played by the Parkes Radio Telescope (indigenous name Murriyang) in the Apollo 11 lunar landing. And many will be aware of the forthcoming Square Kilometre Array (SKA), half of which will be built in Australia. But probably relatively few people really know about the pioneering role played by Australians in this branch of science since its inception after World War II. The Golden Years of Australian Radio Astronomy rectifies…

NIGHT LIFE In an unusual turn of events, the organisers of the international Astronomy Photographer of the Year competition announced in October that they had chosen a new winner for The Sir Patrick Moore Prize for Best Newcomer category, well after the initial list of winners had been formally declared. They didn't explicitly say why, but did note that the category criteria includes the specification that the recipient must have “taken up astrophotography no earlier than a year before the competition opened” and that, following an investigation, the previously announced winner had been disqualified. The new winner is Hannah Rochford, for her photograph ‘The Heart of the Heart – Melotte 15’. The judge, astronomer at Royal Observatory Greenwich, Ed Bloomer, said, “This is a wonderfully balanced image: lots of softness…

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 subscription or renewal to the magazine.…

The discovery of an asteroid inside Venus’ orbit might be the first of a new population in the inner Solar System, suggests a study published in the Monthly Notices of the Royal Astronomical Society. A team of astronomers spotted the asteroid on the night of January 4, 2020, using the 1.2m Samuel Oschin telescope at Palomar Observatory. Later measurements showed it always remains within Venus’ orbit. At the discovery team's request, the Pauma band of indigenous peoples have named the worldlet 594913 ‘Ayló'chaxnim, (pronounced ai-LOH-chakh-nym), meaning ‘Venus Girl’ in the group's Luiseño language. It's as red as asteroids in the main belt, indicating its possible origin, and it spans 2 kilometres — surprisingly large for an innerSolar-System object. Team lead Bryce Bolin (Caltech) notes that seeing a large object early…

NZ PHOTO COMPETITION Australian Sky & Telescope is proud to be a sponsor of the competition.…

The past few months have seen a flurry of oppositions, giving us some great views of Earth's planetary cousins. But alas, that season is behind us, especially for Mars, which won't come to opposition again until January 2025. And we're now about to lose some of the planets for a while as they scoot around to the other side of the Sun for their conjunctions, so let's make the most of what we still can see. We'll start off with Mercury (mag. 0.5, dia. 8.7”, Jan. 18). The innermost planet is often hard to spot, as it usually remains close to the horizon and is frequently obscured by buildings, trees and hills. It begins January at inferior conjunction (between the Sun and Earth) on the 7th, but from mid-month will…

In my opinion, all the most interesting stars are variable stars… with the possible exception of our own very ‘interesting’ Sun. Variables are stars that are either very massive and explosively unstable; old and gently shaking themselves apart; or young and unpredictable. And they're all associated with nebulae of one form or another, hence their photogenic popularity and astrophysical intrigue. V380 Orionis is one such object, 1,500 light-years away in the constellation of Orion within the reflection nebula NGC 1999. Actually, when we look at V380 Ori what we're seeing is a 10.2-magnitude object that is in fact a multiple-star system, comprising a B9 primary and a lowermass secondary, separated by less than 33% of the distance of the Earth to the Sun. The spectral type B9 implies a mass…

PREVIOUSLY, I HAVE DESCRIBED my picks of some of winter's finest open clusters. Now I'd like to share a selection of favourite summer clusters. There are, of course, far too many to choose from, including some of the most famous clusters in the sky. Our tour on these pages will take us to a few of those famous clusters, but many others are overlooked members of this class of deep sky object. We'll begin with the Pleiades (M45), a star cluster that features prominently in many of the world's diverse cultures. I've always liked the poet Alfred, Lord Tennyson's reference: Many a night I saw the Pleiads, rising thro’ the mellow shade, Glitter like a swarm of fire-flies tangled in a silver braid. Last summer, on an evening with excellent…

Donald Goldsmith and Martin Rees The Belknap Press of Harvard University Press, 2022 185 pages, ISBN 978-0674257726 US$25.95, hardcover “THE ARGUMENTS IN this book point to one striking conclusion,” write the authors of The End of Astronauts. “We do not need astronauts as space explorers.” Their reasoning for using robots over people is rational and authoritative — what you'd expect from the UK's Astronomer Royal (Rees) and a respected astrophysicist-author (Goldsmith). So it's worth hearing them out, even if your initial reaction is, “No more astronauts? What are you thinking?” Goldsmith and Rees answer that question methodically. For one, they claim that machines’ abilities are rapidly converging on ours. In the coming decades, they write, “robots and artificial intelligence will grow vastly more capable, closing the gap with human capabilities…

THERE HAVE BEEN tens of thousands of words written by and about Robert Evans OAM, a visual astronomer par excellence who died on November 8 at the age of 85. One of Bob's guiding principles was to be of service, and he made it contagious; he had the knack of motivating people to do things in such a way as to leave everyone better off. By 1986, of the 13 supernovae that had discovered visually (as opposed to being detected photographically), 11 of them had been found by Bob, using, in his words, a “25cm portable Newtonian… of dubious and elementary construction”. At that time he noted that one advantage of visual observing was the possibility of immediate notification of discoveries. Many of the supernovae he discovered were found before…

Good science takes time. That's not a popular refrain when there's a new space telescope sending down crystal-clear views of the infrared universe nearly every day. But astronomers drinking from the firehose that is the James Webb Space Telescope need time to interpret some of their most anticipated data: the spectra of exopianet atmospheres. A study published in the journal Nature Astronomy urges caution in interpreting the chemical fingerprints of these alien worlds. While molecule detections to date aren't in question, determining their abundance is trickier, says Julien de Wit, who led the study with graduate student Prajwal Niraula (both at MIT). Niraula, de Wit and colleagues found that the models astronomers use to decode spectra become imprecise when faced with high-quality Webb data. For example, one group of astronomers…

The James Webb Space Telescope has imaged Neptune and its gossamer rings. We haven't detected some of these rings since Voyager 2's flyby of the planet in 1989. Neptune itself appears dull in the image because trace amounts of methane in its atmosphere absorb the near-infrared wavelengths Webb was observing. However, high-altitude clouds appear bright because their methane ice crystals reflect sunlight before they can absorb it. A thin line at the equator also appears bright, because this is where the atmosphere warms and sinks. The image also shows seven of Neptune's 14 known moons, including the brilliant Triton, covered in highly reflective frozen nitrogen, at upper left. Triton is much brighter than Neptune, which is why it reveals Webb's characteristic diffraction spikes.…

It's still early days in the operational life of the James Webb Space Telescope, yet it's safe to say that its initial images are blowing minds all across the globe. The two pictures on these pages are a perfect case in point, and it's probably no surprise that the Webb team chose this region of space, the so-called ‘pillars of creation,’ as one of the telescope's early targets — a similar image from the Hubble Space Telescope blew minds back in 1995. The images show just a small part of the central region of the Eagle Nebula (Messier 16), located more than 6,000 light-years away in the direction of the constellation Serpens. The three pillars are towering clouds of gas and dust that cocoon a multitude of newly bom stars……

Meade now offers a compact astrograph system for budding imagers. The Meade 15cm f/4.1 LX85 Astrograph Reflector Telescope (US$1,999.99) is a scope-and-mount combination that's designed for both visual observing and astrophotography. The OTA is a Newtonian reflector having a BK-7 glass primary mirror with a focal length of 610 mm. The scope includes a 2-inch, dual-speed, Crayford-style focuser. The mount is Meade's LX85 German Equatorial Go To model operated with its AudioStar hand controller (with 30,000-plus objects in its database). Each purchase includes a 26mm Super Plössl eyepiece, a 2-to-1¼inch eyepiece adapter with brass compression rings, 2-inch eyepiece extension tube, 8 × 50 finderscope, dual mounting rings and 4kg counterweight. A 12V DC power source (not included) is required. Meade meade.com…

WHEN Early December 1 am Late December Midnight Early January 11 pm Late January 10 pm These are daylight saving times. Subtract one hour if daylight saving is not applicable. 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 around so the label “Facing NE” is right-side up. About halfway from there to…

The year commences with a couple of meteor showers to see — one is a challenge for southern observers, while the second is well placed. First up is the Quadrantids, a very active (~100 meteors per hour) shower that has a radiant below the northern horizon for most AS&T readers, but which can sometimes produce a meteor or two that shoots southward into view. The shower is active from December 26 to January 12, with a peak around the 4th. Keep a look out in the hours before dawn; alas, observers in the western half of Australia will find that moonlight and the dawn twilight will interfere. The second shower is the Alpha Centaurids, which, as its name suggests, has its radiant in Centaurus in the far southern sky, making…

IMAGING AS THE NEAREST STAR, the Sun is the most dynamic object you can observe in the sky. A nearly perfect sphere of incandescent plasma, it's loaded with fascinating details that change by the minute. And at long last, solar activity is on the rise. Solar Cycle 25 is already on track to produce lots of active regions, sunspots and flares. Here's how you can get in on the imaging action. Areas of interest The Sun is close enough to reveal its churning atmosphere through a properly equipped telescope of any size. By happy coincidence, it appears around a half degree in diameter — the same apparent size as the Moon. This is one reason we get total solar eclipses, which allow for brief, unfiltered views of the Sun's outer…

Christopher A. Roosa University of Nebraska Press, 2022, 176 pages, ISBN 978-1-4962-3334-9, US$29.95, hardcover The golden years of the space age are now so distant that it's hard to recall the tension of that era. But those who were intimately connected with the US's quest to reach the Moon cannot forget. One such is Christopher Roosa, whose father, Stuart, Apollo 14 command module pilot, orbited the Moon 34 times. Roosa book recounts what it was like to grow up in the frenzy of the space race, when astronaut fathers were hardly ever home and family lives were strained. “Life was not a fairytale,” he writes in this new account of his life.…