Innholdsfortegnelse for July - August 2022 i Australian Sky & Telescope

A NEW INSTRUMENT on a powerful telescope has enabled astronomers to discover another planet circling our nearest stellar neighbour, Proxima Centauri. The find brings the star’s exoplanet tally to three candidates (one of them confirmed). The newest of the worlds, Proxima Centauri d, would make an unpleasantly hot place to live, orbiting its faint red star every five days. But the method by which the astronomers detected the planet, by measuring the minute wobble of its host star, might well lead to the discovery of more habitable worlds. More massive and/or closer-in planets exert greater gravitational influence on their stars, creating stronger radial velocity signals. Earth, on the other hand, induces a motion of only 10 cm/s on the Sun. To find other Earths, improving instrument precision only the first…

The origin of the universe may seem an impossible subject to study. After all, according to the Planck spacecraft, the Big Bang — the brilliant event that gave birth to our cosmos — occurred 13.8 billion years ago. Nevertheless, we do see signs of this primaeval fireworks display today, in the nearby universe. For one thing, most galaxies rush away from ours. For another, the Big Bang’s afterglow pervades space — Microwaves still carry news from an era just 380,000 years after the Big Bang, long before stars shone. Amazingly, we even have clues from a much earlier epoch. Mere minutes after the Big Bang, the extreme temperature of the plasma filling the universe triggered nuclear reactions, producing elements that survive to this day. The universe at that time was…

Throughout winter, the crooked, asymmetric star patterns of Centaurus ride above the southern horizon like the rigging of a wrecked pirate ship. And there’s certainly treasure to be found here: Omega (ω) Centauri, or NGC 5139, the largest globular cluster in the Milky Way. It’s legitimately vast, containing several million stars; most globs have a few hundred thousand to perhaps one million. At magnitude 3.9, the cluster is fairly bright, and at declination –47°, is easy for most southern observers to see. Omega Centauri has even been spotted from as far north as southern Canada. You don’t need too much dark adaptation to spot it with the naked eye, and binoculars provide an impressive view. Once, on a dinosaur dig, I watched a hive of bees relocate between homes. After…

There’s only one comet likely to be magnitude 10 or brighter during the closing months of winter, and that will once again be the distant C/2017 K2 (PANSTARRS). This slow-moving object will begin July in Ophiuchus and drift into Scorpius during the first week of August, staying within the bounds of that constellation for the rest of the month (except for a very brief incursion into Libra on August 23–24). C/2017 K2 will make its closest approach to Earth (1.8 a.u.) on July 14, after which its slow intrinsic brightening will be at least partially offset by its increasing distance from us. Consequently, the comet is expected to only brighten by two or three tenths of a magnitude during July and August, remaining in the region of 8.5 to 9…

IN OCTOBER 2007 I attended celebrations in Moscow for the 50th anniversary of Sputnik 1. Space Age ironies were on full display. The festivities highlighted both the militaristic motivations that launched us off Earth, and the belief in an enlightened, unified human future that drove, and still drives, many involved in space exploration. Post-Soviet Russia, though experiencing upheavals, seemed plausibly on a path toward a peaceful, open society. Several Russian scientists shared with me in private the traumas they’d lived through. Following the Soviet collapse, their research programs had been stretched thin, but they’d had, at least on paper, plans for bold new planetary missions. And in 2007 we made plans, at least on paper, to work together in exploring our common Solar System. Now, along with the cities of…

A COUPLE OF YEARS AGO, amateur astronomer Morgan Amos graduated from a 100-mm starter scope to a 30-cm Dobsonian. What he received via the mail order was not quite what he expected. He ended up with a “monstrous, difficult-to-handle” beast “in a casket-sized box”. Nevertheless, he was certain it would be the scope for him, given a little adapting. And he has certainly done some of that. The first order of business was transport — the scope was simply too large and bulky to move in one piece, and even the mount alone was a hefty load. So Morgan decided to put it on a dolly. He could easily have bought a dolly, but he made his own from scratch using wood, and put hard urethane wheels underneath to roll…

Venus has enthralled humanity since the dawn of time with its brilliant presence in the twilit sky. And yet the second planet from the Sun jealously guards its secrets under a roiling, cloud-enshrouded atmosphere. There is renewed interest in the planet, with several new missions on the horizon. But the Japan Aerospace Exploration Agency (JAXA) orbiter Akatsuki (‘Dawn’ in Japanese) is already there. Venus’ notorious sulfuric clouds occupy altitudes between about 48 and 70 kilometres above the planet’s surface. The clouds are further subdivided into upper, middle and lower levels. Below 56.5 kilometres, the clouds contribute to the infamous greenhouse effect that keeps the Venusian surface permanently out of view. Above that, there’s a whole other phenomenon: The top cloud layer speeds around the planet at 100 metres per second…

GHOSTLY RINGS of radio emission spanning a million light-years, dubbed Odd Radio Circles (ORCs), are a recent discovery. They emit no radiation other than radio waves. And we’re only starting to understand what made them. Ray Norris (Western Sydney University) published the discovery of the first four ORCs in 2021, having found three in data from the 36-dish Australian Square Kilometre Array Pathfinder (ASKAP). Another uncovered in archival data brought the tally to five. It took months, he says, to go from the first flush of excitement to confirming that ORCs were a new phenomenon. Now, in a study to appear in the Monthly Notices of the Royal Astronomical Society, Norris and colleagues report that they have taken a closer look at the first-discovered ORC using the 64 dishes that…

This image tells the story of a pulsar as it speeds through space via a combination of visible light (red, brown and black), collected by the Gemini telescope through a hydrogen-alpha filter, and high-energy photons detected by the Chandra X-ray Observatory (blue). PSR J2030+4415 is a city-size stellar core that whirls around three times every second, 1,630 light-years away in Cygnus. When Martijn de Vries and Roger Romani (both at Stanford University) first observed its X-ray emission, they saw not only the pulsar and the glow of energetic particles trapped within its magnetic field, but also a thin, straight beam that trailed off the edge of the discovery image. So de Vries and Romani asked for additional observations to determine the beam’s true extent. The result: 15 arcminutes across the…

The South African Radio Astronomy Observatory has released a striking series of images showing the complex and chaotic centre of our galaxy, part of a study to appear in the Astrophysical Journal. Unaffected by the large quantities of dust that obscure this region in visible light, radio waves reveal a scene teeming with star birth and star death as well as nearly 1,000 mysterious radio filaments. Discovered in the early 1980s, the filaments can extend up to 150 light-years and appear highly organised. Some even come in pairs or clusters. Cosmic rays streaming from our galaxy’s centre, perhaps from its resident supermassive black hole, might compress and illuminate the galaxy’s ambient magnetic field. Besides the filaments, our galaxy’s inner 650 light-years are also home to young, massive stars, puffy remnants…

WHO WERE THE FIRST astronomers? Who got the systematic study of the night sky started? To answer those questions, first of all we need to narrow their scope. No doubt our very distant ancestors were looking at the night sky and wondering for many millennia, forming patterns among the stars and telling stories about the images they imagined there. They may have used the movements of the night sky to tell the seasons. But for most of that time, those ancestors could not write, and so we have no records about what they saw or thought. So our question becomes… who were the first astronomers of whom we have knowledge? Who left behind some written record of their observations? The crown appears to go to the Babylonians (sometimes called the…

THIS IS THE DAWN OF A NEW Age of Venus. After a dry spell lasting more than 25 years, NASA has finally selected not one but two missions to our neighbouring planet: the VERITAS orbiter, launching as soon as 2027, and the DAVINCI flyby and atmospheric probe, launching in 2029. The European Space Agency will follow with the EnVision orbiter in the early 2030s. What broke the drought? “To some degree, it had just been so long that it was becoming kind of an embarrassment,” says David Grinspoon (Planetary Science Institute), a co-investigator on DAVINCI. Just as important, however, was that exoplanet researchers had started advocating for Venus missions. “They’re already starting to find exo-Venuses. What hope do we have of figuring things out that many light-years away if we…

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 and look north nearly halfway from horizontal to straight up. There’s Arcturus! NOTE The map is plotted for 35° south latitude…

This year’s Southern Delta Aquariid meteor shower is expected to be active from July 12 to August 23, with a maximum on July 30/31. This is one of the best showers of the year, with up to 25 meteors per hour not uncommon for observers who have dark skies (although over the last 40-plus years there have been a couple of reports of rates of up to 40 per hour). You can expect to see meteors that are of medium speed, mostly white and usually faint; occasionally some of them will leave trains. The Moon will be out of the way, so all we need to do is keep our fingers crossed for some good weather. Our second shower is the Alpha Capricornids, which is active from July 3 to…

Overhead tonight, many of the visible stars are members of the Scorpius–Centaurus OB Association: Alpha, Beta and Tau Scorpii; Alpha, Gamma and Delta Lupi; Kappa Cen and Rho Ophiuchus among them. Closely connected with this Association are the Lupus star forming clouds. These dark clouds comprise one of the main low-mass, star-forming regions within 700 light-years of us, and they host this issue’s target, the protostar RU Lupi. RU Lup is classified CTTS — classical T Tauri star — with a visual magnitude range of 9.8 to 12.9. These types of stars are irregular variables that can flicker, fade, flair or even remain stable. Much of this activity is due to accretion from a surrounding circumstellar disc. In fact, the star and its disc are best considered one object unified…

TWO SUPERMASSIVE black holes in the heart of a distant galaxy are tightly entwined, offering unique insights into how such mergers unfold. One of the black holes gorges on surrounding material, creating a radio jet that happens to point almost directly at Earth. Such objects, called blazars, are known for their volatility, typically flaring and dimming randomly. But when team member Anthony Readhead (Caltech) began observing the blazar, PKS 2131–021, in 2008, he noticed something unusual. “It was varying not just periodically, but sinusoidally,” Readhead says. To confirm that the years-long pattern was real, he and his team went trawling through older data, ultimately going back to archived data 45 years old. Upon seeing the peaks and troughs in the earlier data, “we knew something very special was going on,”…

OF EVERYTHING WE KNOW about our Solar System, the number of planets orbiting the Sun might seem like one thing that we should have nailed down by now. And yet, there have been rumors of another world, lurking beyond Neptune. This is no dwarf planet like Ceres or Pluto, but a world with some heft, possibly five to 10 times as massive as Earth. The primary hints of its existence come from a paltry number of diminutive icy objects whose orbits all appear to be bunched up in one quadrant of the Solar System. For the past six or so years, Konstantin Batygin (Caltech) has been at the forefront of the hunt for this elusive world, dubbed by some as Planet X, by others as Planet Nine (sorry, Pluto). “Here’s…

I LIVE IN A FOREST. The only view of the sky I get from my house is a tiny notch above my roof, viewable from my driveway. To make matters worse, my sky is badly light polluted. So every telescope I’ve made has to fit into my car for the drive out of town and be at least tolerably easy to set up and take down in the dark. I also dream of travelling to distant places see parts of the sky inaccessible from my home. Somehow, I don’t think I’ll be taking my 32-cm binocular scope on an aeroplane, though. Nor do I trust baggage handlers with a classic Dobsonian or even a refractor in a padded case. What I need is a scope with enough aperture to be…

We’re all going to be treated to three very different oppositions during July and August — one planet, Saturn; one dwarf planet, Pluto; and one asteroid, Vesta. Something for everyone! Opposition occurs when the Sun and a Solar System body are 180° apart as seen from the vantage point of Earth. That is, the Sun is in one direction from us and the other body is in the exact opposite direction. This means that when the Sun is setting in the west, the planet or other body is rising in the east and is therefore visible essentially for all of the night. Note that the date of opposition is not the same as the date of closest approach — the two are, however, very close, and for practical purposes a…

WHILE THE NAME RIGHTLY implies that the Sky-Watcher Evoguide 50DX was designed as a guidescope, it’s more versatile than that. Fitted with eyepieces, it can serve as a high-quality finder and even a small telescope (more about that later). And with the optional Evoguide 50ED Field Flattener (US$105), it’s a decent wide-field astrograph that performs well with sensors as large as APS format. The Evoguide we borrowed from Sky-Watcher for this review still carries the 50ED name badge on the side of the tube, and the company says the optical tube has not changed since its introduction as the 50ED several years ago. The 50DX now includes a nice two-ring mounting bracket with soft-tipped locking thumbscrews. This bracket attaches to either a ‘finder’ stalk with a dovetail foot that fits…

Two amateur astronomy initiatives — one by an individual, and one a group effort — have been awarded the prestigious 2022 Berenice and Arthur Page Medal, Australia’s highest honour for amateur astronomers who conduct scientific work. The presentation was made online on 16 April during the National Australian Convention of Amateur Astronomers. Normally, the Page Medal is awarded to an individual, but this year the judges from the Astronomical Society of Australia (ASA) — the nation’s body of professional astronomers — decided that two recipients should be recognised for their work. The first recipient comprises a group of six friends who make up The Backyard Observatory Supernova Search (BOSS) Team, who monitor distant galaxies to detect supernovae. The team alerts professional telescopes to swing into action and study these phenomena…