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Australian Sky & TelescopeAustralian Sky & Telescope

Australian Sky & Telescope January 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.

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astrophotos – be in it to win it

FOR A LONG TIME, undertaking astrophotography from light-polluted city and suburban skies had been difficult. But fortunately today there are lots of tricks and techniques you can use to successfully take impressive deep sky shots from your backyard, as our article beginning on page 56 explains. From filters that remove some of the damage of streetlights, to post-processing techniques that clean up and enhance your data, there’s bound to be something that will help you in your quest for the perfect shot. And perfect shots are what we showcase on pages 12–17, as we once again celebrate New Zealand’s annual Harry Williams Astrophotography Competition. I think you’ll agree that the images are absolutely superb. There’s just something about the combination of New Zealand’s dark, clear skies and otherworldly landscapes that brings…

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solid evidence of water ice on the moon

AFTER MORE THAN A DECADE of tantalising but inconclusive hints, new research shows convincingly that patches of water ice lie exposed on the floors of many permanently shadowed lunar craters. Shuai Li (University of Hawai‘i) and colleagues make use of near-infrared spectra from India’s Chandrayaan 1 orbiter, which operated between 2008 and 2009, and report the findings in the September 4 Proceedings of the National Academy of Sciences. Water ice can remain inside these craters because their floors are never exposed to direct sunlight, the consequence of a lunar spin axis that’s nearly (within 1½°) perpendicular to the ecliptic plane. Temperatures at these always-dark crater floors are extremely low, plunging as low as –233°C. Any local traces of water vapour — delivered, say, by a small comet’s impact — will freeze…

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astronomers ‘weigh’ beta pictoris b

ASTRONOMERS HAVE OBTAINED a precise new mass measurement for Beta Pictoris b, a gas-giant planet 63 light-years from Earth. Ignas Snellen and Anthony Brown (both at Leiden University, The Netherlands) reported the measurement on August 20 in Nature Astronomy. The exoplanet came to light in 2008, when the European Southern Observatory’s Very Large Telescope in Chile captured the infrared glow of the planet still in the throes of formation. But in the decade since, astronomers have been struggling to nail down the planet’s detailed properties, especially its mass. They suspected the planet has a mass several times that of Jupiter, due to its influence on the star’s large debris disk. Later mass estimates based on direct imaging ranged from 4 to 17 times Jupiter’s mass. Now, Snellen and Brown have used exquisite…

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scientists successfully predict shape of the solar corona

SCIENTISTS ATTEMPTED TO predict the shape of the Sun’s corona as it would appear during the total solar eclipse on August 21, 2017. Observations confirmed that they got the broad strokes right. The corona, an intricate crown of thin, super-hot plasma around the Sun, expresses our star’s hidden magnetic angst. Its charged particles respond to the magnetic field by twisting into loops, bands, and even erupting into interplanetary space. Solar physicists led by Zoran Mikić (Predictive Science) report August 27 in Nature Astronomy that they can accurately predict the appearance of the corona one week in advance — an important milestone on the path to predicting the oncoming solar wind. The team offered a new model of the Sun’s outer layers that takes into account how their heat and magnetic fields stimulate…

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in brief

Parker Probe’s first perihelion NASA’s Parker Solar Probe spacecraft flew to within 24 million kilometres of the Sun’s photosphere during its fly-by on November 6, Australian time. The event marked the mission’s first-of-several perihelion passages, as the spacecraft begins its orbits of the Sun. At this perihelion, the craft had to endure intense solar radiation and plasma at temperatures of 2 million degrees Celsius. • JONATHAN NALLY Impact shaped ice giant Scientists have long known that a long-ago impact likely caused Uranus’s strange tilt. Jacob Kegerreis (Durham University, UK) and colleagues explored this concept further by simulating more than 50 impact scenarios. In the July 1 issue of Astrophysical Journal, the team concludes that 4 billion years ago, a rock-and-ice protoplanet with at least twice Earth’s mass collided with Uranus and knocked it over.…

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sibling rivalry incited eta carinae’s explosion

NEW ANALYSIS OF THE MASSIVE Eta Carinae star system supports the idea that the system once had three stars — but only two survived. Eta Carinae experienced its so-called Great Eruption about 170 years ago: a blast that resembled a supernova in ferocity but left the massive primary star intact. Now, a pair of studies appearing in the October issue of Monthly Notices of the Royal Astronomical Society have tracked down faint reflections of the explosion’s light as it scatters off of nearby interstellar dust. The roundabout path of the light echo gives astronomers a real-time view of the long-ago goings-on. By taking a spectrum of the reflected light, Nathan Smith (University of Arizona) and colleagues measured the speed of material at different stages of the explosion. The first phase showed relatively…