"A European spacecraft orbiting a distant comet has finally answered a question we've all been wondering: What does a comet smell like? 'It stinks,' says Kathrin Altwegg, a researcher at the University of Bern in Switzerland who runs an instrument called ROSINA that picked up the odor. The European Space Agency has posted a full rundown of the comet's BO on its website. The mix includes ammonia (NH3), hydrogen sulphide (H2S), formaldehyde (CH2O) and methanol (CH3OH). Of course, anyone visiting the comet would be wearing a spacesuit (on top of that, the sense of smell is notoriously numb in space). Nevertheless, taking a whiff of this comet would be like sharing a horse barn with a drunk and a dozen rotten eggs."