Scientists Sniff Smelly Comet

Combine the stench of a horse stable, some rotten eggs, and a little formaldehyde, and you have the scent of Comet 67P/C-G. The European Space Agency’s Rosetta spacecraft has detected what scientists describe as a rich array of molecules in the comet’s coma, including ammonia (NH3), sulphur dioxide (SO2), and methane (CH4). Kathrin Altwegg, principal investigator of the ROSINA instruments—which sniffed out the comet’s odor—describes what these findings could help us understand about how our solar system, and even life itself, came to be.