Free Astronomy Magazine May-June 2015

Editor in chief Michele Ferrara Scientific advisor Prof. Enrico Maria Corsini Publisher Astro Publishing di Pirlo L. Via Bonomelli, 106 25049 Iseo - BS - ITALY email info@astropublishing.com Internet Service Provider Aruba S.p.A. Loc. Palazzetto, 4 52011 Bibbiena - AR - ITALY Copyright All material in this magazine is, unless otherwise stated, property of Astro Publishing di Pirlo L. or included with permission of its author. Reproduction or retransmission of the materials, in whole or in part, in any manner, with- out the prior written consent of the copyright holder, is a violation of copyright law. A single copy of the materials available through this course may be made, solely for personal, non- commercial use. Users may not distrib- ute such copies to others, whether or not in electronic form, whether or not for a charge or other consideration, without prior written consent of the copyright holder of the materials. The publisher makes available itself with having rights for possible not characterized iconographic sources. Advertising - Administration Astro Publishing di Pirlo L. Via Bonomelli, 106 25049 Iseo - BS - ITALY email admin@astropublishing.com ASTROFILO l’ May - June 2015 BI-MONTHLY MAGAZINE OF SCIENTIFIC AND TECHNICAL INFORMATION FREELY AVAILABLE THROUGH THE INTERNET English edition of the magazine S U M M A R Y Nova 1670, a mystery almost solved 345 years after the appearance of a nova in Cygnus, a small team of astronomers has established that that event was most likely caused by the explosive fusion of two normal stars. The chemical and physical characteristics of the remnant left by the event are wholly suitable to a type of explosion... 4 Mars: the planet that lost an ocean’s worth of water A primitive ocean on Mars held more water than Earth’s Arctic Ocean, and covered a greater portion of the planet’s surface than the Atlantic Ocean does on Earth, according to new results published online in Science on 5 March 2015. An international team of scientists used ESO’s Very Large... 12 Hubble sees supernova split into four images by cosmic lens Astronomers using NASA's Hubble Space Telescope have spotted for the first time a distant supernova split into four images. The multiple images of the exploding star are caused by the powerful gravity of a foreground elliptical galaxy embedded in a massive cluster of galaxies. This unique observation will... 14 Looking deeply into the universe in 3D The MUSE instrument on ESO’s Very Large Telescope has given astronomers the best ever three-dimensional view of the deep Universe. After staring at the Hubble Deep Field South region for only 27 hours, the new observations reveal the distances, motions and other properties of far more galaxies than ever before... 17 The largest ocean is on Ganymede Those who thought that the richest salt water reservoirs belonged to the Earth should think again, as it is now certain that on Ganymede, the largest natural satellite in our solar system, there is a subterranean ocean whose volume exceeds that of all our oceans put together. An extraordinary piece of news from... 22 An old-looking galaxy in a young universe A team of astronomers, led by Darach Watson from the University of Copenhagen, used the Very Large Telescope’s X-shooter instrument along with the Atacama Large Millimeter/submillimeter Array (ALMA) to observe one of the youngest and most remote galaxies ever found. They were surprised to discover... 28 A grand extravaganza of new stars This dramatic landscape in the southern constellation of Ara (The Altar) is a treasure trove of celestial objects. Star clusters, emission nebulae and active star- forming regions are just some of the riches observed in this region lying some 4000 light-years from Earth. This beautiful new image is the... 34 Unusual asteroid suspected of spinning to explosion A team led by astronomers from the Jagiellonian University in Krakow, Poland, recently used the W. M. Keck Observatory in Hawaii to observe and measure a rare class of “active asteroids” that spon- taneously emit dust and have been confounding scientists for years. The team was able to measure... 36 Dusty cloud passes galactic centre black hole A supermassive black hole with a mass four million times that of the Sun lies at the heart of the Milky Way galaxy. It is orbited by a small group of bright stars and, in addition, an enigmatic dusty cloud, known as G2, has been tracked on its fall towards the black hole over the last few years. Closest... 38 Waiting for Philae’s reawakening The adventuresome Philae landing on the nucleus of 67P/Churyumov-Gerasimenko has partly com- promised its mission, due to the unexpected impossibility to recharge its batteries. While waiting for the probe’s possible return to activity, plentiful are the discoveries made in the two and a half... 40