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Celestial firework marks nearest galaxy collision

A spectacular galaxy collision has been discovered lurking behind the Milky Way, the closest such system ever found. “Kathryn’s Wheel” was found during a special wide field survey of the Southern Milky Way with the UK Schmidt Telescope in Australia. Such systems are very rare and arise from “bull’s-eye” collisions between two galaxies of similar mass.

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Rosetta studies Comet 67P at perihelion

ESA’s Rosetta spacecraft has witnessed 67P/Churyumov–Gerasimenko make its closest approach to the Sun (perihelion) at 3:03am BST on 13 August, when the comet came within 116 million miles of our nearest star. Rosetta’s measurements suggest the comet is currently spewing up to 300kg of water vapour and a metric tonne of dust every second, creating dangerous working conditions for the spacecraft.

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Cassini’s last close flyby of Saturn’s moon Dione

NASA’s Cassini spacecraft will zip within 295 miles of Saturn’s moon Dione on Monday, 17 August — the final close flyby of this icy satellite during the probe’s long mission. After close flybys of other moons in late 2015, Cassini will depart Saturn’s equatorial plane to begin a year-long setup of the mission’s grand finale: repeatedly diving through the space between Saturn and its rings.

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Researchers explain why the Greenwich prime meridian moved

In 1884, a delegation of international representatives convened in Washington, D.C. to recommend that Earth’s prime meridian marking zero degrees longitude should pass through the Airy Transit Circle (ATC) at the Royal Observatory in Greenwich, England. But according to the GPS receivers of surveyors and smartphones of London tourists today, why does the line of zero longitude run 102 metres east of the ATC?

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Chilean astronomical site becomes world’s first international dark sky sanctuary

The International Dark-Sky Association has just announced that the site of the Association of Universities for Research in Astronomy (AURA) Observatory in the Elqui Valley of northern Chile has been recognised and designated as the first International Dark Sky Sanctuary in the world. The site will be known as the “Gabriela Mistral Dark Sky Sanctuary” after the famed Chilean poet.