And it ain't pretty.
Be thankful you don't have access to a Futurama-esque Smell-o-Scope, because scientists have now managed to detect what a comet smells like - and it's a combination of rotten eggs and horse pee.
The European Space Agency's Rosetta Spacecraft is getting set to land on Comet 67P/Churyumov-Gerasimenko on 12th November. But at the same time, the comet is moving closer to the Sun and becoming more "active" - which basically means that gases are beginning to escape from the centre of the comet through its cracks and pores.
Rosetta thankfully has mass spectrometers on board to measure the chemical composition of this gas, and it's given us a pretty good clue as to what the comet smells like.
As Mark Strauss explains for io9, the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has detected:
Carbon monoxide (CO)
Carbon dioxide (CO2)
Hydrogen sulfide (H2S)
Hydrogen cyanide (HCN)
Sulfur dioxide (SO2)
Carbon disulphide (CS2)
That might not mean much to you, but this is how Kathrin Altwegg, the principal investigator for ROSINA, describes it:
"The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde. This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide. Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the 'perfume' of our comet."