Cometary Jet
Series of images shows part of the comet before (left), during (middle), and after (right) it releases a jet of gas. ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Temperatures are rising on the duck-shaped Comet 67P. As its lopsided orbit brings it closer to the sun, the comet’s ice is rapidly boiling off into gas. On July 29, these forces set loose one giant cometary fart—a “dramatic outburst event proving so powerful that it even pushed away the incoming solar wind,” says the European Space Agency.

Thankfully, the Rosetta orbiter wasn’t in the line of fire. Its cameras did catch the outburst in action though, and based on those images, scientists estimate that Comet 67P’s fart clocks in at 10 meters per second, at least. (In case you’re curious, it’s rumored that human farts travel at speeds of 10 feet per second, but we couldn’t find the source.)

What would such an astronomical outburst smell like? The brave Rosetta spacecraft got a whiff of what came out of the comet, analyzing the gas’s components with ROSINA, its onboard spectrometer. After the outburst, the gasses surrounding the comet contained 7 times the hydrogen sulfide (that stuff that causes a rotten egg smell) and 4 times the methane compared to usual. So it’s actually similar to a human fart.


As the comet moves toward its perihelion—its closest approach to the sun, on August 13—its activity is picking up, and these sudden and unpredictable outbursts could occur at any time, says ESA. That’s probably all right with Rosetta, whose goal is to study what makes up the comet. Maybe now we can tell what it had for lunch.