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Australian Sky & TelescopeAustralian Sky & Telescope

Australian Sky & Telescope

November/December 2019

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.

Paragon Media Pty Ltd
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8 Issues


access_time1 min.
here comes the sun

AWE-INSPIRING. SPELLBINDING. Unforgettable. A total solar eclipse tends to bring out the superlatives when those who’ve seen one grasp for words to describe the experience. If you’ve witnessed one of these natural wonders then you’ll know what I mean. Aside from one brief occasion when I was a kid, I’ve seen only one total solar eclipse… and indeed I was awestruck by the experience. So much so, in fact, that I had to be reminded to remove my ‘eclipse glasses’ when totality arrived — I was so dumbfounded by the whole thing that I had forgotten to take them off! Phenomena such as eclipses and transits serve to remind us of how vast the Solar System is, and are live demonstrations of celestial mechanics of the kind we don’t get to…

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australian sky & telescope

EDITORIAL EDITOR Jonathan Nally ART DIRECTOR Lee McLachlan CONTRIBUTING EDITORS John Drummond, David Ellyard, Alan Plummer, David Seargent, Con Stoitsis EMAIL info@skyandtelescope.com.au ADVERTISING ADVERTISING MANAGER Jonathan Nally EMAIL jonathan@skyandtelescope.com.au PUBLISHER Ian Brooks SKY & TELESCOPE INTERNATIONAL EDITOR IN CHIEF Peter Tyson SENIOR EDITORS J. Kelly Beatty, Alan M. MacRobert SCIENCE EDITOR Camille M. Carlisle NEWS EDITOR Monica Young ASSOCIATE EDITORS Susan N. Johnson-Roehr, Sean Walker OBSERVING EDITOR Diana Hannikainen ART DIRECTOR Terri Dubé ILLUSTRATION DIRECTOR Gregg Dinderman ILLUSTRATOR Leah Tiscione Founded in 1941 by Charles A. Federer Jr. and Helen Spence Federer…

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amateur finds another interstellar visitor

ON AUGUST 30, 2019, Ukrainian amateur astronomer Gennady Borisov, using a newly built 0.65-metre telescope, discovered a rather inauspicious-looking 18th-magnitude comet that has actually turned out to be of remarkable interest. Orbital computations reveal it to be travelling through the Solar System on a strongly hyperbolic orbit, having an eccentricity of around 3.4. Eccentricity indicates whether an orbit is circular, elliptical, parabolic or hyperbolic. C/2019 Q4 (Borisov) thus becomes the second interstellar visitor to have been found during the past two years. The first such object of interstellar origin found — given the name ‘Oumuamua and a catalogue number 1I/2017 U1 — did not reveal any cometary activity, but mysteriously displayed clear non-gravitational acceleration as it moved away from the Sun. According to cometary expert Zdenek Sekanina, the most reasonable explanation is…

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german-russian satellite to map the x-ray sky

THE SPEKTRUM-RÖNTGEN-GAMMA (Spektr-RG) satellite, a long-delayed and much-modified X-ray astronomy package, launched successfully from the Baikonur Cosmodrome in Kazakhstan on July 13. Once Spektr-RG reaches a stable solar orbit 1.5 million kilometres from Earth, at Lagrangian point L2 , two telescopes aboard will commence mapping the X-ray sky. The first is the German space agency’s Extended Röntgen Survey with an Imaging Telescope Array (EROSITA); the second is the Russian-built Astronomical Röntgen Telescope – X-ray Concentrator (ART-XC). Each telescope contains multiple modules of concentric mirror pairs. X-rays will skip off these mirrors at grazing incidence angles, like smooth pebbles off a pond, before coming to a focus on the detectors. EROSITA’s vision is the sharper, with 18-arcsecond resolution, and its wide field of view will enable it to survey the full sky eight times…

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tess finds hundreds of planet candidates in southern sky

NASA’S LATEST exoplanet hunter, the Transiting Exoplanet Survey Satellite (TESS), has found more than two dozen new worlds that have been confirmed in follow-up observations. Scientists shared their findings late July at the mission’s first science conference since the spacecraft’s launch in April 2018. TESS’s goal is to find planets circling bright stars within 200 light-years of Earth. The spacecraft has scanned all 13 sectors of the Southern Hemisphere sky during its first year of operations. So far, TESS scientists have identified 993 planet candidates in 12 of the 13 southern sectors; 271 of them are smaller than Neptune. A total of 28 of these exoplanets have been confirmed as real via follow-up observations. One of the newest systems, anchored by a small, M dwarf star called GJ 357, hosts three exoplanets.…

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hubble constant tension continues

A NEW STUDY of a special class of red giant stars fuels a dispute about the rate at which today’s universe is expanding. The universe’s expansion rate has changed throughout time. However, the crux of an ongoing debate is that observations of the early universe predict a current expansion rate that doesn’t match measurements of galaxy recession speeds. Observations of the cosmic microwave background (CMB) pin today’s expansion rate, also called the Hubble constant (H ), between 66.9 and 67.9 km s-1 Mpc-1 . However, measurements of galaxies’ recession speeds — based on so-called standard candles such as Cepheid variable stars — find H to be significantly higher, between 73 and 76 km s-1 Mpc-1 . Now, Wendy Freedman (University of Chicago) and colleagues have employed red giant stars — specifically, those…