Comet Siding Spring Animation

The sharp-eyed science camera on Europe’s Rosetta comet orbiter caught a view of the probe’s fuzzy shadow when controllers guided the spacecraft just a few miles over its subject’s nucleus last month.

If it were possible to breath in space, one would smell a pungent aroma of rotten eggs, ammonia, vinegary sulphur dioxide and toxic hydrogen cyanide coming from comet 67P/Churyumov–Gerasimenko, according to sensors on the Rosetta mission.

Where did the two natural satellites of Mars, Phobos and Deimos, come from? For a long time, their shape suggested that they were captured asteroids. However, the shape and course of their orbits contradict this hypothesis. Two independent and complementary studies now provide an answer: these satellites formed from the debris of a gigantic collision between Mars and a protoplanet one-third its size.