Innholdsfortegnelse for January 2020 i Australian Sky & Telescope

THE LIGO-VIRGO COLLABORATION has so far announced 11 detections of gravitational-wave surges based on data collected during its first two observing runs. Each surge comes from the merger of distant compact objects. Now, an independent team sorting through the public data archive has found seven additional black hole merger candidates. Tejaswi Venumadhav (Institute for Advanced Study) and his colleagues developed their own data analysis pipeline to look specifically for black hole mergers. This is unlike the approach taken by the LIGO and Virgo collaborations, who look at data with ‘eyes wide open’ to catch anything and everything, explains LIGO spokesperson Patrick Brady (University of Wisconsin, Milwaukee). The more focused approach provides greater sensitivity to spot quieter signals, Venumadhav said during a recent colloquium at Harvard University’s Black Hole Initiative. The…

DARK SKY ADVOCATES ARE pushing for New Zealand to set a global precedent as the world’s first Dark Sky Nation. All over the country, communities are banding together to protect their nocturnal nightscapes from the insidious spread of light pollution, and momentum is growing. Fourteen initiatives are currently underway, all aiming to gain formal recognition for the quality of their night skies from the International Dark-Sky Association (IDA) in Tucson, Arizona. Founded in 1988, the IDA’s mission is to “preserve and protect the nighttime environment and our heritage of dark skies through environmentally responsible outdoor lighting”. The New Zealand efforts include a really significant initiative to control light pollution across the Wairarapa region, so that it can gain accreditation as an International Dark Sky Reserve. If successful, it would be…

Here’s our digest of active space missions for 2020. Included are astrophysics, space weather, planetary and solar and stellar observation missions; we omit missions that primarily observe Earth. Planet locations are marked for January 1, 2020. Mission statuses are current (to the best of our knowledge) as of late 2019. Those orbiting Earth are primarily categorised by research topic, which can be a bit subjective, and we’ve lumped all science projects aboard the International Space Station under ‘ISS’. Also listed are planned launches, though these are always subject to change. 2020 is a Mars year. Four missions from four separate space agencies are looking to make the journey to the Red Planet in 2020, adding to the growing fleet of craft both on and orbiting Mars. China may also begin…

Our destination this month lies in the northeastern reaches of Orion, the Hunter. Set 73 and 74 Orionis near the south edge of your field of view, and 69 and 72 Orionis near the north edge. You’ll find yourself looking at a sprawling, complicated field with chains of bright stars, doubles, at least one cluster and more. Right away you’ll notice an arc of bright stars running east-west like a lopsided smile, bounded by HD 44033 in the east and Nu (ν) Orionis in the west. Just south of Xi (ξ) Orionis, four 6th- and 7th-magnitude stars make a miniature arc within the larger one. Just a bit to the west lies the open cluster NGC 2169. It’s a small cluster, only about 5’ across as seen from Earth, but…

This issue we’re going through the process of making and lodging a variable star observation. TT Monocerotis is a Mira-type variable that ranges in brightness from magnitude 7.2 to 14.4 over a period of 318 days. I’ve chosen TT Mon for several reasons: It’s an under-observed star with a bright maximum and a good sequence of comparison stars; it suits the warmer months by being best observed only every week or two; and not least, it’s a finder object for next issue’s really exotic target. First, we locate the field. Between Sirius and Procyon, Delta Mon points southwest to Alpha Mon. All four stars are plotted, if not labelled, on the all-sky chart in this issue. Now with a finder scope, halfway between Alpha and Beta Mon you can easily…

It’s a great opportunity for a zillionaire philanthropist to make history with a theatrical and scientifically rich exploration first. EVERYTHING WE THINK WE KNOW about the universe beyond our Solar System has come from photons and a few grains of interstellar dust. But that near-complete material isolation is about to end. Our system apparently buzzes with objects from elsewhere in the galaxy. It’s time to go out and meet one. The existence of extraterrestrial comets isn’t a surprise. We’ve known for decades that, unless there’s something seriously wrong with our ideas about planet formation, they must exist. Building planets through gravitational accretion is messy. Planet assembly should be causing a constant exodus of bodies loosed from the grip of their home stars. If anything, it seemed a little strange that…

NASA HAS ANNOUNCED A ROBOTIC mission, named the Volatiles Investigating Polar Exploration Rover (VIPER), will head to the lunar south pole to hunt for water ice and characterise the lunar soil. A four-wheeled rover about the size of a golf cart, VIPER will be built at the Johnson Space Flight Center. It is projected to cost US$250 million dollars. VIPER was preceded by the Resource Prospector mission concept. That was scrapped in 2018, but its instruments are being repurposed for other missions. VIPER is scheduled for a late 2022 landing, which would put it on the lunar surface before NASA’s ambitious ‘boots back on the Moon’ goal for the Artemis program, currently set for late 2024. Data collected by the rover will help to construct global water resource maps of…

JUPITER MAY BE THE KING of the planets, but — right now, at least — Saturn is the king of moons. Astronomers Scott Sheppard (Carnegie Institution for Science), David Jewitt (UCLA) and Jan Kleyna (University of Hawai‘i) have announced the discovery of 20 new moons circling the ringed planet, putting Saturn’s total at 82 compared with Jupiter’s 79. The moons are each around 5 kilometers in diameter. The team used the 8.2-metre Subaru telescope atop Maunakea, Hawai‘i, to find the moons. Sheppard had previously led a team in discovering 10 new moons around Jupiter, announced last year, using the 6.5-m Magellan-Baade reflector at Las Campanas and the 4-m Blanco reflector on Cerro Tololo. “Using some of the largest telescopes in the world, we are now completing the inventory of small…

HALF A CENTURY AGO, Uranus, Neptune and Pluto marked the ultimate in planetary mystery. Even as people set foot on the Moon and spacecraft sped past Venus and Mars, the outermost worlds seemed to yield their secrets as slowly as they revolve around the Sun: Uranus, twice as remote as Saturn, completing an orbit once every 84 years; Neptune, more than 1.5 billion kilometres beyond, taking a leisurely 165 years to do the same; and Pluto, more than a billion kilometres beyond that, its year 248 times longer than our own. Today, scientists marvel at exquisite images from our recent trip to Pluto, but its two giant neighbours still languish. Uranus and Neptune have entertained only one passing spacecraft, Voyager 2, back in 1986 and 1989, respectively. Since then, we’ve…

Eclipses, oppositions, spectacular conjunctions, a close encounter between Venus and the Pleiades and many more celestial sights await stargazers this year. December 2019 15 The Geminids peak this morning, but the waning gibbous Moon will interfere with the viewing of this reliable meteor shower. 22 Solstice. Today the hours of daylight are longest in the Southern Hemisphere, and the Sun is furthest south in the sky. 26 A partial solar eclipse will be visible from Darwin and across northern Australia. January 11 Mercury is at superior conjunction (ie. on the other side of the Sun) today, and so can’t be seen. Wait until March for good views. 11 Today there will be a pre-dawn penumbral lunar eclipse — see eclipse box. 14 Both Saturn and Pluto reach conjunction today (ie.…

Is Lavoisier the only lunar crater named for a scientist who faced the guillotine? The brilliant French chemist famed for his recognition that oxygen is a chemical element, Antoine-Laurent Lavoisier was one of many nobles who lost their heads during the French Revolution. But the crater Lavoisier remains along the western limb of the Moon, ironically near von Braun, another noble who supported a deposed regime. These two craters are so near the limb (about 80°W longitude) that they appear as foreshortened ellipses and are rarely observed. Yet the larger craters Gauss and Humboldt are both near 80°E longitude and are frequently targeted by observers. The latter two craters are twice as big as Lavoisier and von Braun, and are readily observed in early evenings, while the western limb craters…

THE MOON ISN’T MADE OF GREEN CHEESE, and the Milky Way isn’t a splash of mother’s milk intended for Hercules. It’s true that no one has believed these things for centuries. But many other astronomical truths have a far more recent origin. Take, for example, our understanding of spectacular deep sky objects such as the Orion, North America and Lagoon nebulae. Any budding amateur astronomer today will tell you these are glowing clouds of ionised hydrogen. And novice astrophotographers all know that it takes equipment sensitive to the red light of hydrogen-alpha emission to capture good images of them. But despite being common knowledge today, neither of these facts was known until well into the 20th century. The first proof that nebulae could be clouds of gas rather than aggregations…

Andy Casely is a spatial scientist whose day job involves modelling and monitoring extreme weather and financial risk. But his other passion is astrophotography. In 2019, he won the Planets, Moons and Asteroids category of the prestigious Insight Investment Astronomy Photographer of the Year 2019 awards for his sequence of Mars images showing a dust storm enveloping the planet. What got you into astronomy? I grew up in Scotland, and the starry nights in the Scottish Highlands probably drew me in. As a 12-year-old I learned the constellations and planets and have been completely hooked since then. I recall my parents asking if it was ‘just a passing fad’ before getting my first telescope in 1992. Little did they know! What was your first telescope? It was a 60-mm Vixen…

The bird’s melancholy cry only enhanced the harmony of the silent spectacle before us. THAT NIGHT, the trees surrounding the shoreline of the lake looked like an army of crowned kings, standing with arms interlocked. Halted at the water’s edge, they seemed to be patiently waiting for a glimpse of a secret and solitary queen, who was about to pass before them. My friend and I also were in attendance, perched high above the treetops on a smooth, rocky outcrop that overlooked the lake. As darkness approached, day reluctantly gave way to night and its accompanying sounds in the surrounding ponds and bush. Not far off, a nightjar called its name, while lonely tree frogs called out for a mate. The long, wide wings of a heron creaked as it…

ASTRONOMERS USED a fast radio burst, a powerful 40-microsecond-long flash of radio waves, to evaluate the state of the nearly invisible gas around an intervening galaxy. The mass of the hot, gaseous halo that surrounds most massive galaxies is often on par with the mass of all the stars in the galaxy itself. Yet it largely evades detection. It’s both very hot — ‘cooler’ clouds of some 10,000K (9,700°C) float within a hotter, million-degree atmosphere — and sparse, with only a couple hundred atoms within the space of a child’s balloon. So astronomers observe the gas indirectly, by the way it absorbs the light of background sources. Previous observations have suggested that halos tend to be turbulent, with high-density clouds embedded in the rarefied gas. Yet the astronomers reported in…

Faraway galaxies act as torches, lighting up a piece of the cosmic web from when the universe was only about 2 billion years old. Computer simulations predicted this large-scale structure decades ago, yet the sparse gas bridging one galaxy cluster to another is difficult to detect directly. But in the October 4 issue of Science, Hideki Umehata (RIKEN Cluster for Pioneering Research, Japan) and colleagues published an image (right) of a 3-million-light-year-long section of this gas. Using the Multi Unit Spectroscopic Explorer (MUSE) on the European Southern Observatory’s Very Large Telescope in Chile, Umehata’s team zeroed in on a distant collection of galaxies, collectively known as SSA22. These galaxies, bursting with newborn stars (white dots) and/or hosting a gas-guzzling black hole (not shown here), irradiate the sparse hydrogen gas that…

OVER THE PAST FEW DECADES , spectacular photos taken by landers and rovers from the surface of Mars have joined the ranks of the Space Age’s most iconic images. One reason the photos have such appeal is because they paint a picture of an Earthlike environment. Rolling hills, layered mesas, fields of boulders, distant horizons, wispy clouds streaked across an endless, clear sky… the scenery could be out of a movie set somewhere in the desert of Western Australia. There is a familiarity to it, a timelessness evoked by geology laid bare, a sense of déjà vu — you feel like you may have driven through here before… In reality, of course, nothing could be further from the truth. The ‘Earthiness’ of Mars is a cruel illusion. While Mars is…

ASTRONOMY 2020 YEARBOOK Every astronomer needs the Astronomy 2020 yearbook. Australian-produced, it is packed full of essential information to plan your observing sessions. Included is a complete guide to what’s visible in the night sky, including Moon phases, planets, comets, eclipses and meteor showers, plus star maps and a month-by-month viewing guide. $29.95 plus postage & handling 2020 AUSTRALASIAN SKY GUIDE An ideal yearbook for beginners, the easy-to-read 2020 Australasian Sky Guide provides a month-by-month guide to what can be seen with the naked eye, along with lots of interesting facts and figures, detailed descriptions of special astronomical events, and planetary data. $16.95 plus postage & handling ASTRONOMY 2020 CALENDAR Featuring amazing celestial photography from the annual David Malin Awards, the Astronomy 2020 Calendar provides a guide to what’s visible…

Red Rose, proud Rose, sad Rose of all my days! Come near me, while I sing the ancient ways:… And thine own sadness, whereof stars, grown old In dancing silver-sandalled on the sea, Sing in their high and lonely melody. Come near, that no more blinded by man’s fate, I find under the boughs of love and hate, In all poor foolish things that live a day, Eternal beauty wandering on her way… Sing of old Eire and the ancient ways: Red Rose, proud Rose, sad Rose of all my days. —William Butler Yeats, excerpted from To the Rose Upon the Rood of Time Many consider Yeats to be the greatest English-language poet of the 20th century. His work contains some notable references to the stars. For instance, the final…

With confirmation of its interstellar origin, C/2019 Q4 (Borisov) has now been given the alternative designation of 2I/Borisov (with the ‘I’ meaning interstellar). The comet has, not surprisingly, attracted a good deal of attention, but probably the most surprising thing about it is the lack of surprises! Essentially, it is indistinguishable from any small Solar System comet. Intrinsically quite faint, 2I is estimated to have a nucleus of several hundred metres diameter made up of the same material as typical comets belonging to the Sun’s family. The only ‘oddities’ appear to be some greater similarities with dynamically evolved solar comets than with typical first arrivals from the Oort Cloud. Indeed, 2I seems to belong to the class of ‘carbon-chain depleted’ comets, of which those belonging to Jupiter’s family are typical…

THE DYING STAR HAD ABOUT 10 TIMES the mass of our Sun and had just lost the ability to fuse elements in its core. Without the outward pressure of fusion to hold back its own crushing gravity, the inner core collapsed within seconds into a 20-kilometre-wide sphere of neutrons. The outer core of the star immediately crashed onto this abruptly smaller and superdense core at 23% the speed of light. A titanic shock wave explosively rebounded off the star’s neutron core, completely disrupting its outer layers in a star-shattering Type II supernova. The intensely sudden and cataclysmic death of the star was briefly brighter than the entire Milky Way galaxy. Around 6,500 years later Chinese astronomers saw a brilliant ‘guest star’ in the pre-dawn sky near Zeta (ζ) Tauri on…

EVERYTHING ABOUT THE NEW 25-cm f/12 classical Cassegrain from Taiwan-based Guan Sheng Optical (GSO for short) says 21st century. There’s its carbon-fibre truss-tube design, quartz optics, mirror coatings with 96% reflectivity, cooling fans, and a dual-speed, 3¼-inch Crayford-style focuser for starters. But to understand where my head was at while testing the telescope we borrowed from Agena AstroProducts for this review, you need to turn the calendar back to a time well before the Apollo Moon landings and indulge me for a bit of nostalgia. Back then amateur astronomy was very different from now. The big-aperture Dobsonian revolution and its emphasis on deep sky observing wouldn’t begin for more than another decade. The same was true for the astrophotography boom that followed the introduction of popularly priced Schmidt-Cassegrain telescopes. Owning…

The premier Australian amateur astronomy conference, the National Australian Convention of Amateur Astronomers (or NACAA; pronounced ‘Nakka’) is only a few months away. Hosted every two years in a different city by the local astronomical society, in 2020 it is the turn of Parkes and Central West Astronomical Society. Parkes, of course, is home to the CSIRO’s famous radio telescope, otherwise known as ‘the Dish’. NACAA 2020 (nacaa.org.au) will be held across the Easter weekend, April 10–13. The venue will be the aptly named Starlight Lounge at the Services Club on Short Street, Parkes. A preliminary program is already available (nacaa.org.au/2020/programme), with the final program to be available on the website by March. The event will comprise technical sessions, scientific presentations and workshops, the latter including introductory and advanced workshops…