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Australian Sky & Telescope

Australian Sky & Telescope

July - August 2021

Australian Sky & Telescope is a world-class magazine about the science and hobby of astronomy.  Combining the formidable worldwide resources of its venerable parent magazine with the talents of the best science writers and photographers in Australia, Australian Sky & Telescope is a magazine produced specifically for the Southern Hemisphere’s astronomers.

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Paragon Media Pty Ltd
R 80,38
R 428,71
6 Issues

in this issue

1 min
bits of theia might be hidden in earth’s mantle

EVIDENCE FOR the impact that created the Moon might lie far beneath our feet. The leading theory for the Moon’s formation is that a roughly Mars-size object, dubbed Theia, struck Earth around 4.5 billion years ago. At the virtual 52nd Lunar and Planetary Science Conference, Qian Yuan (Arizona State University) and his colleagues suggested that bits of Theia might remain as two dense masses deep in our planet’s mantle. The two continent-size masses are known as large, low-shear-velocity provinces (LLSVPs). Seismic waves traversing our planet’s interior have revealed these to be roughly 1,000 kilometres tall and several thousand kilometres wide, stuck on either side of the Earth’s core like misshapen earmuffs. Inspired by recent results dating the LLSVPs to 4.45 billion years old, Yuan and his colleagues simulated the evolution of Theia’s remains…

1 min
new studies suggest the universe is expanding faster

TWO INDEPENDENT GROUPS have measured the Hubble constant, the universe’s current rate of expansion, and their results have deepened the tension in an ongoing controversy. Observations of the far-away (early) universe, particularly the cosmic microwave background emitted 380,000 years after the Big Bang, lead to a current expansion rate of 67 km/s per megaparsec. But near-universe observations point to a higher value of 73 km/s/Mpc. Adam Riess (Space Telescope Science Institute) has been leading an effort to tie Cepheid variables, a ‘standard candle’ typically found in nearby galaxies, to Type Ia supernovae, another standard candle that can be seen from farther away. Improving on previous work, Riess’s team combined precise distances from the Gaia satellite with Hubble Space Telescope brightness measurements of 75 Cepheids in galaxies hosting Type Ia supernovae. In the…

2 min
amateur astronomers reveal galactic echoes

IN A PROMISING proof of concept, a professional astronomer has teamed up with five amateurs to capture the echoes of long-ago mergers in nearby galaxies. The team is now looking to expand their number of galaxies — and observers. Duilia de Mello (Catholic University of America) is leading the Deep Images of Mergers (DIM) project to capture the faint shells of stars on the outskirts of a class of galaxies thought to have had a merger in their past. The shells are likely the remains of a less massive galaxy disrupted during the collision. To test this idea, de Mello, who is from Brazil herself, engaged five Brazilian amateurs — Marcelo Wagner Silva Domingues, Cristóvão Jacques Lage de Faria, João Antônio Mattei, Eduardo de Jesus Oliveira and Sérgio José Gonçalves da Silva…

1 min
the great red spot gets smaller… but stronger

JUPITER’S GREAT RED SPOT (GRS) has been shrinking ever since regular observations began in 1878, from about 48,000 kilometres across to its present width of about 15,000 km. But recent encounters with other storms shrank it further, leading some to predict the iconic spot would come to an end. However, new data and analysis by a team of amateur and professional astronomers revealed that those encounters also pumped up the Great Red Spot’s energy, likely extending its life. Between 2018 and 2020, a series of smaller oval storms battered the GRS at a greater frequency than before, distorting the storm’s shape and tearing ‘flakes’ off its edge. In early 2019, amateurs circulated an alert and began systematic observations to provide context to data from NASA’s Juno mission. Professional astronomers also conducted observations…

2 min
pathway to pluto

LAST YEAR JUPITER PROVED an able guide to finding Pluto, but the gas giant has since moved on, leaving the dwarf planet by itself in the wilds of eastern Sagittarius. However, a distinctive asterism and several bright telescopic stars point the way this season. As long as your scope can dig down to Pluto’s magnitude of 14.3, with a careful approach you should be able to find this Holy Grail of astronomical challenges Under a dark sky, a 20-cm telescope should be up to the task. An excellent place to start is the small asterism called the Terebellum — four stars brighter than 5th magnitude in the shape of a kite with Omega (ω) Sagittarii at its peak. Use the charts above and a wide-field eyepiece to locate Pluto on the…

1 min
using the star chart

WHEN Early June 10 pm Late June 9 pm Early July 8 pm Late July 7 pm These are standard times. 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…