Australian Sky & Telescope

November - December 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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6 Nummer

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1 min
next-generation space observatory

AS IT WRITE THIS, all is on track for a December 18 launch of the James Webb Space Telescope (JWST, named after an early head of NASA), the space observatory that will enable us to look back in time through the cosmos to earliest eras following the Big Bang. Optimised to detect infrared wavelengths, it should be able to spot the very first generation of galaxies and thereby give us insight in the formation and evolution of the first generation of stars. JWST is a ground-breaking machine, not just in what it hopes to accomplish in scientific investigation but also in its design and the technologies it uses. Our article in this issue (turn to page 26) explains the many amazing technological achievements that have been needed to produce a telescope…

3 min
nasa’s insight reveals first look inside mars

NASA’S INSIGHT MISSION has reported the first direct observations of another rocky planet’s interior structure. The results — a surprisingly thin crust, a one-layer mantle and a large core — will help scientists understand how Mars formed and evolved. Measuring marsquakes wasn’t just a matter of sending a seismometer to Mars; in a sense, the scientists also had to wait for the planet to come to them. While Insight recorded 733 marsquakes since early 2019, the vast majority were weak, surface tremors. “Of course, when you’re in the middle of the situation, it can feel as if ‘Oh my god, it’s not working!’” says Simon Stähler (ETH Zurich, Switzerland). The team waited several months after the seismometer’s deployment before a shake occurred deep enough to probe the planet’s interior, says seismometer…

2 min
‘liquid water’ spots below martian surface might be clay

RESEARCHERS HAVE IDENTIFIED dozens of radar-bright spots within the layers of ice and sediment deposits at Mars’ south pole. These discoveries follow the 2018 announcement of a large radar-bright area beneath those deposits that researchers said might indicate a subglacial lake. However, the additional finds, as well as further experiments and analysis, suggest that the spots might be ancient clay deposits instead of liquid water. In a study published in the July Geophysical Research Letters, Aditya Khuller (Arizona State University) and Jeffrey Plaut (Jet Propulsion Laboratory) used the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard the European Space Agency’s Mars Express orbiter to chart the subsurface boundary where the polar deposits end and the Martian interior begins. Their investigation revealed dozens of new smaller radar-bright regions at…

1 min
resolving the mars methane mystery

New measurements from NASA’s Curiosity rover show that methane concentrations near the Martian surface vary on a daily cycle, a finding that could help reconcile conflicting data. Curiosity first sniffed the gas on June 15, 2013, and has since found background methane levels between 0.2 and 0.7 parts per billion in volume (ppbv). But in 2019, the European Space Agency’s ExoMars Trace Gas Orbiter failed to find methane after several months of operation. ExoMars examines sunlight that has travelled through the atmosphere’s upper layers and should be able to detect particle concentrations as low as 0.05 ppbv. Then John Moores (York University, Canada) realised that the discrepancy could boil down to the time of day: Curiosity takes methane measurements at night, when the atmosphere is cool and calm, while ExoMars…

1 min
witnessing gravitational instability

Astronomers have reported a gravitationally unstable disk circling the young star Elias 2-27. Gravitational instability is one path to planet formation: When disks become massive enough, they may collapse directly into planets or form spiral arms that trap material for future planet formation. A team led by Teresa Paneque-Carreño (now at Leiden University, The Netherlands) used the Atacama Large Millimeter/submillimeter Array to spot a hallmark wiggle, a signature of gravitational collapse, in the spiral arms of the disk around Elias 2-27. The wiggle is a disturbance in the disk’s rotation on scales coinciding with instability-induced spiral arms. Paneque-Carreño’s team saw the wiggle by observing the motions of carbon monoxide in the disk, which traces the harder-to-observe hydrogen gas. Furthermore, a companion study concluded that Elias 2-27’s disk has 17% the…

1 min
kepler finds possible outcast earths

ASTRONOMERS HAVE UNCOVERED four candidate Earth-mass rogue planets by searching for microlensing events observed with NASA’s Kepler satellite. Rogue planets drift aimlessly through space after ejection from their stellar system during the early stages of planet formation. When a star or planet passes in front of a distant star, it acts like a magnifying lens to temporarily brighten the background star, an effect known as microlensing. Rogue planets are best spotted via microlensing because they’re too faint to detect directly. However, the smaller the ‘lens,’ the shorter the microlensing event; Earth-mass planets magnify background stars for only a couple of hours, making them difficult to differentiate from stellar flares. A team lead by Iain McDonald (now at Open University, UK pored through data from the rejuvenated Kepler mission, dubbed K2, to recover…