Someone light a match.
In a study making people everywhere giggle, researchers found that much of the upper atmosphere of Uranus is hydrogen sulphide. That's the same compound responsible for some odours familiar here on Earth, including farts and rotten eggs.
"If an unfortunate human were ever to descend through Uranus' clouds, they would be met with very unpleasant and odiferous conditions," Patrick Irwin from the University of Oxford, one of the study's authors, said in a news release.
On the other hand, the smell could quite literally be the last thing you notice.
"Suffocation and exposure to the -200ºC atmosphere made of mostly hydrogen, helium and methane would take its toll long before the smell," Irwin said.
Scientists used data from the Gemini North telescope in Hawaii to take a long-distance sniff of the atmosphere above the clouds of Uranus and solve one of the stinkiest mysteries of the solar system. While some scientists have long thought Uranus had high concentrations of hydrogen sulphide, others believed the planet would contain ammonia, as had been observed in Jupiter and Saturn.
The Gemini data, published this week in journal Nature Astronomy, confirmed that Uranus stinks.
"Now, thanks to improved hydrogen sulphide absorption-line data and the wonderful Gemini spectra, we have the fingerprint which caught the culprit," said Irwin.
Or maybe he who smelt it, dealt it...