Innholdsfortegnelse for August/September 2023 i Australian Sky & Telescope

SPECTRUM READING THE ARTICLES in this issue about Williamina Fleming and E.E. Barnard, has made me reflect on how much we owe to these and other giants of the astronomy world, now long since gone. This holds true for all aspects of astrophysics — e.g. planetary studies, solar physics — but perhaps for none more so than the pioneers of the deep sky. Without their tireless efforts, our species would have had absolutely no clue about the nature, size and scale of our cosmos and where we fit into it. Just think — it’s not much more than 100 years ago that most astronomers believed that our Milky Way galaxy was the full extent of the universe. They had no idea that there were other galaxies beyond, nor were they…

Meteorite crashed into New Jersey home When Suzy Kop stepped into her father’s bedroom on May 8, she saw a black, mango-size rock on the floor, its broken surface exposing a creamy interior. Looking around, she spotted two holes in the ceiling, and she knew something wasn’t right. Some 15 minutes before Kop had arrived (around 12:30pm), there was a report of a fireball in the area. As it happened, the heavy end of that falling star crashed through the roof of the home in Hopewell Township, New Jersey. The meteorite struck the floor with such force that it rebounded and punched a second hole in the ceiling before landing back on the floor. Unsure what to do, Kop called the Hopewell police for assistance. A hazmat team arrived to…

THE SUN HAS been busy lately. Activity, including sunspots and flares, began picking up steam last year before suddenly ramping up even more in early 2023. The sudden rise prompted some to wonder if the current solar cycle is becoming more active than scientists had predicted. The Sun goes through 11-year cycles of magnetic activity during which its magnetic poles swap places. The last cycle (Cycle 24) was one of the quietest cycles on record, and the Solar Cycle Prediction Panel, an international group of experts, forecast that the current cycle (Cycle 25) would be on par with it or only slightly more active. Lisa Upton (Southwest Research Institute), co-chair of the panel for Cycle 25, holds that the current activity still matches the panel’s prediction. “It has been a…

Forty of the 50 plates included in Barnard’s monumental A Photographic Atlas of Selected Regions of the Milky Way were obtained with the Bruce astrograph at Mount Wilson in 1905. Afterwards, the instrument was returned to Yerkes Observatory and set up in a small dome between the main observatory building and Barnard’s house on the shore of Lake Geneva. Although the transparency at Yerkes was generally not as good as at Mount Wilson, Barnard did succeed in obtaining some excellent plates there. After Barnard’s death in 1923, Yerkes director Edwin Brant Frost hired Frank E. Ross, who moved into Barnard’s house. Ross was tasked with taking over Barnard’s program of Milky Way photography. He realised that by comparing recent plates with Barnard’s from 20 years earlier, he could find stars…

EVENINGS WITH THE STARS Last issue I took a look at the northern half of the giant curl of bright stars that is Scorpius, the Scorpion. This time we’re going to dive down into the constellation’s southerly half — a region brimming with wonders. Let’s start our tour with the two bright and close stars that together form the tip of the Scorpion’s stinger: 1.6-magnitude Lambda (λ) Scorpii (Shaula) and 2.7-magnitude Upsilon (υ) Scorpii (Lesath). They’re sometimes known as the Cat’s Eyes, though one eye is much brighter than the other. Every winter I watch the pair’s progress across the sky, leading the way for Sagittarius. Shaula and Lesath are only 36′ apart; having two bright stars apparently so close together is very rare. Shaula is the 24th brightest star…

Rainbow Astro RST-135 US price: $3,895 (head only) rainbowastro.com What we like Small and portable Accurate Go To Works in equatorial or alt-az mode What we don't like Large periodic error Lacks periodic-error correction Hand controller steep learning curve THE ADAGE THAT ‘bigger is better’ is not aging well, at least not when it comes to astrophotography. The current trend is toward portable imaging with smaller telescopes, which means smaller mounts are needed to put them on. And along with this new emphasis on portability, a new technology has arrived — the ‘harmonic’ mount. Such units use ‘strain-wave’ gearing technology, originally developed for industrial robotics, to create compact but very strong mounts capable of handling a hefty telescope without the need for heavy counterweights to balance the load. My first…

ONE OF THE GREAT advantages of John Dobson’s telescope design is that it enables amateur astronomers to build big telescopes. New Zealand ATM Hamish Barker went that route some years ago with a 20cm f/6 scope that he admits was “unpopular with my wife and son when we went camping in our 1976 VW camper”. So he bought an old but excellent 25cm f/5 mirror and set out to build something a bit more compact but still quick to set up. Hamish had seen Mel Bartels’ elegant 33cm (13-inch) f/3 Zip Dob, which curls up like a fern, and that inspired him to try folding his scope as well. He quickly realised that a single fold would make the scope short enough to suit his needs, and a little sketching…

HOW TO SUBMIT YOUR IMAGES Gallery showcases the finest astronomical images that our readers submit. Send your best shots to photos@skyandtelescope.com.au. See skyandtelescope.com.au/contributions/ for guidelines.…

Astronomers armed with new James Webb Space telescope (JWST) images have gotten under the high-altitude skin of the mini-Neptune dubbed GJ 1214b. The results, published in Nature, suggest that this planet’s atmosphere is composed of some combination of water, methane and hydrogen cyanide, all wrapped thickly in highly reflective clouds or haze. GJ 1214b swings around its red dwarf star every 1½ days, so it’s scorchinghot. But it maintains an atmosphere, and from the world’s lightweight density, astronomers had suspected that water in some form would be a major constituent. But multiple attempts to take the atmosphere’s spectrum as the world passed in front of its star were stymied by what appeared to be highaltitude clouds or hazes. Now, JWST observations of the full orbit have enabled a team led…

Aluminium can reveal which stars were born in fast-paced galaxies. Such galaxies quickly enrich themselves with carbon, nitrogen and oxygen as stellar winds and supernova explosions spew these elements into space; newborn stars then inherit the three elements, which catalyse the hydrogen-tohelium fusion reaction via the so-called CNO cycle. The CNO cycle also speeds up the production of aluminium, so the faster carbon, nitrogen and oxygen emerge from stars, the more aluminium arises too. The CNO cycle converts some of the carbon and oxygen a star is born with into nitrogen-14. Later in the star’s life, two helium-4 nuclei hit some of this nitrogen-14 and create neon-22, a neutron-rich isotope with 10 protons but 12 neutrons. Subsequent nuclear reactions with this neon cause some of those neutrons to end up…

BINOCULAR HIGHLIGHT Near the eastern border of Sagittarius, the Archer, you’ll find a neat little cross asterism formed by four 5th-magnitude stars: 59, 60, 62 and Omega (ω) Sagittarii. At 2° tall and 1° wide, the asterism is big enough to be spotted with the naked eye, and it makes a fun binocular target. Look for it about halfway between the 4th-magnitude star Psi (ψ) Capricorni and the Teapot of Sagittarius. In the Chinese constellations, this group of four stars is known as Gǒu Guó, or Dog Territory. The Alexandrian astronomer Ptolemy recorded it as the ‘Tetrapleuron,’ which means quadrilateral. In his 1603 Uranometria, Johann Bayer Latinised the Greek ‘Tetrapleuron’ to ‘Terebellum,’ and in 1801 Johann Bode included the Terebellum in his Uranographia atlas. Sometime thereafter astronomers stopped labelling it,…

We have two planetary oppositions to cover this issue, plus the usual inner planet conjunctions as well as the southern spring equinox. Let’s start as we always do, with the innermost planet, Mercury (mag. 0.3, dia. 7.5˝, Aug. 10), which begins August in the western evening sky. Reaching greatest elongation (i.e. angle from the Sun) of 27° on the 10th, you’ll find that it has a companion — Mars, just 5° away — for about a week. (The colour contrast between the two will be quite noticeable, Mercury being white and Mars being a ruddy reddish hue.) After this, Mercury then heads for the horizon and reaches inferior conjunction (between the Earth and the Sun) on September 6. About a week later you’ll find it skimming the eastern horizon before…

Edward Emerson Barnard is known today for a number of things. His photographic work is highly regarded, particularly his images published in 1927 in A Photographic Atlas of Selected Regions of the Milky Way. But he was also one of the most accomplished visual observers in history. Barnard’s discovery in 1892 of Jupiter’s fifth moon (which he denoted Jupiter V and which is now called Amalthea) was the first addition to the gas giant’s retinue since Galileo, and the last planetary satellite to be discovered visually. He also identified the star in Ophiuchus that possesses the highest proper motion (about 10″ per year). At a distance just shy of 6 light-years, Barnard’s Star, as we now know it, is second only to the Alpha Centauri system overall. In 1884 Barnard…

Observers use aperture masks to improve the view through a telescope, particularly under unsteady seeing. Such masks tend to fall into one of three categories. The first is off-axis, or stop-down, masks. These reduce the aperture to minimise the blurring effects of atmospheric seeing and avoid the influence of a central obstruction. These masks can produce occasional crisp, albeit lower-resolution views. The second type is focusing masks for astrophotography, such as those popularised by Pavel Bahtinov, Andrei Oleshko and others. The third kind is apodising masks, which are designed to improve the view by modifying the diffraction properties of the telescope to help resolve close double stars in the eyepiece and on camera. The most common design of the latter type is a two-dimensional, circularly symmetric apodising mask intended to…

Joseph Silk Princeton University Press, 2022 304 pages, ISBN 9780691215235 US$29.95, hardcover BACK TO THE MOON paints an exciting vision of planned human activity on and around the Moon in coming years and decades: crewed bases at craters in the south polar region and larger settlements in lava tubes; an orbiting spaceport, together with communications and data-relay satellites; robot-assisted mining of lunar resources; even tourist resorts. Importantly for author Joseph Silk (and AS&T readers), this expansive view includes giant observatories. Some distinguished scientific experts urge that further exploration of the Moon and beyond be conducted robotically, not by astronauts. But Silk, a renowned astrophysicist at Johns Hopkins University, argues that the train has left the station — whether we like it or not, humans are returning to the Moon. NASA’s…

EXPLORING THE SOLAR SYSTEM is a long game, with travel times measured in years. And the time from when we first propose a mission to when our spacecraft sits on the launch pad, ready to leave Earth or die trying, is often much longer still. In a way, the pace is a return to that of the age of sailing ships, when explorers left home for years at a time — though we modern planetary explorers don’t physically risk our lives, just large chunks of our careers. The Voyager program, originally called the Grand Tour and first proposed in 1969, finally launched in 1977. Between 1979 and 1989, the two Voyagers visited Jupiter, Saturn, Uranus and Neptune, in brief flybys lasting just a few days each. In between were long…

WHEN I WAS 10 years old, nothing captured my imagination more than the canals of Mars and the magnificent (and rather tragic) story Percival Lowell told of a civilisation of intelligent beings having built them to stave off extinction on their dying world. In his 1910 book Mars as the Abode of Life, Lowell described the canals as “Fine lines and little gossamer filaments only, cobwebbing the face of the Martian disk, but threads to draw one’s mind after them across the millions of miles of intervening void.” Soon after I read this, Mars came to opposition in March 1965 — the first I ever observed. With my 60mm refractor, I gazed with all my heart at the tiny, coppery pinhead of light that swam in the field of view.…

ASTRONOMERS HAVE PROVIDED the most direct evidence yet that dark matter does not consist of ultramassive particles. The work, based on supercomputer calculations, suggests that dark matter is instead made up of axions — hypothetical particles so light that they travel through space more like waves. If correct, the researchers’ conclusions would not only help reveal what 85% of matter in the universe is made of; the results could also lead to new physics beyond the standard model. The study was published April 20 in Nature Astronomy. Dark matter is tricky to investigate because it doesn’t emit, absorb or reflect light. So instead, a team led by graduate student Alfred Amruth (University of Hong Kong) looked for the material’s influence on gravitational lensing. In this effect, a galaxy and its…

On February 6, 1923, American astronomer Edward Emerson Barnard lay dying in the upstairs bedroom of his house on the shore of Lake Geneva, Wisconsin, not far from the two telescopes he loved most — the 25cm (10-inch) Bruce astrograph he used extensively to photograph the Milky Way and the Yerkes 1m (40-inch) refractor, the world’s largest instrument of its kind. Few astronomers have achieved Barnard’s distinguished record. His name is forever tied to the eponymous Barnard’s Star in Ophiuchus and the nebulous Barnard’s Loop in Orion. He’s also famously known for his catalogue of 369 dark nebulae — some of which are among the most photogenic objects in the night sky. Perhaps Barnard’s greatest achievement, however, was his magnificent and monumental photographic tour de force, A Photographic Atlas of…

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 North’ is right-side up. About halfway from there to the map’s centre is the bright star Procyon. Go out and look north halfway between the horizon to straight overhead, and there you’ll find Procyon! NOTE The map is plotted…

WHETHER IT’S YOUR first time or 200th, Saturn is an irresistible telescopic sight. The planet brightens to magnitude +0.4 as it inches westward across central Aquarius this year. By opposition on August 27, its globe will span 19.0″ and the rings will extend to 43.1″. The most notable change compared to last year is the narrowing tilt of those rings. Tipped by just 9.0° at opposition, we view the north face of the rings. We’ll continue to do so until March 2025, when they will be presented edge-on. A 60mm telescope magnifying 40× will show the rings easily. Saturn’s diminishing tilt means it’s difficult to observe the entire curve of the dark Cassini Division, which separates the A and B rings. However, the gap should still be easy to make…