Exposed Water Ice on Comet Reveals Clues About Its Evolution

A European spacecraft has spotted water ice on the surface of a comet, shedding new light on the formation and evolution of the icy object. The European Space Agency's Rosetta spacecraft detected relatively large grains of water ice in two different places on the surface of Comet 67P/Churyumov-Gerasimenko, which the probe has been orbiting since August 2014. These big grains may have formed after heat from the sun sublimated (or vaporized) buried water ice, which then recondensed and was redepos