It’s Official: Uranus Has Stinky Clouds That Smell Like Rotten Eggs

Researchers have finally managed to peer into the gas giant's atmosphere and confirm it contains hydrogen sulfide.

Planet Uranus.
NASA Images / Shutterstock

Researchers have finally managed to peer into the gas giant's atmosphere and confirm it contains hydrogen sulfide.

Leave it to the British to turn their noses up at Uranus. A group of universities in England, working together with the California Institute of Technology in Pasadena, have published a study confirming Uranus stinks to high heaven, quite literally.

The research documents the presence of hydrogen sulfide in the planet’s upper atmosphere — the same molecule that gives rotten eggs their pungent smell, Newsweek reports.

The theory is old, as scientists have long speculated that the planet’s main visible cloud layer contains either ammonia ice, similar to Jupiter and Saturn, or hydrogen sulfide ice. But they were never able to prove this theory without solid evidence. This most recent study provides actual proof that Uranus is indeed a stinky, stinky planet.

“If an unfortunate human were ever to descend through Uranus’ clouds, they would be met with very unpleasant and odiferous conditions,” said the study’s lead author, Patrick Irwin, from Oxford University.

The team was able to peer deep into the gas giant’s atmosphere with the help of the Near-Infrared Integral Field Spectrometer (NIFS) at the Gemini North 26-foot telescope in Hawaii.

This powerful instrument — which normally is used for the study of back holes and other objects hiding in the center of galaxies, Newsweek points out — succeeded in detecting the sunlight reflected from Uranus’ atmosphere just above the cloud tops, and eventually identified the signature of hydrogen sulfide molecules, states Space.com.

Until now, such a detailed observation of Uranus was impossible, considering how far the planet is from Earth. But the scoping abilities of the NIFS have managed to zero in on the correct wavelength and spot the hydrogen sulfide gas in the cloud tops as it absorbed light.

According to study co-author Leigh Fletcher, from the University of Leicester, the hydrogen sulfide gas is only present in small amounts in Uranus’ upper atmosphere, which accounts for past difficulties in spotting either ammonia or hydrogen sulfide above the planet’s cloud decks.

“The superior capabilities of Gemini finally gave us that lucky break,” Fletcher explained.

These findings underline the important differences between outer gas giants in our solar system, Uranus and Neptune, and the slightly larger inner gas giants, Jupiter and Saturn. Irwin points out that these differences go back in time to the moment these planets were formed and have been largely influenced by their distance from the sun.

“The implications of this are that during the formation of the solar system, Uranus (and probably Neptune) formed at a greater distance from the sun where it was cold enough that both ammonia and hydrogen sulfide were in condensed icy form and thus easily incorporated into the growing planetary embryos that would eventually become Uranus (and Neptune),” Irwin said in a statement.

At the same time, Jupiter and Saturn were formed closer to the sun, where “ammonia would be preferentially in gas form and thus less easily incorporated,” he explained.