Scientists confirm Uranus smells like rotten eggs

Credit: Courtesy of NASA via Wikimedia Commons Credit: Courtesy of NASA via Wikimedia Commons

The planet Uranus not only looks like an egg, but also smells like one.

Planetary scientist Leigh Fletcher and his team from the University of Leicester in England analyzed Uranian chemicals and determined that Uranus’s atmosphere has a rotten egg smell.

“Uranus’ upper clouds are made of hydrogen sulfide — the same molecule that gives rotten eggs their noxious odor,” explains science writer Lisa Grossman.

Scientists have long suspected that there was some hydrogen sulfide in Uranus’s atmosphere.

But, confirming this hypothesis has been a challenge, since Uranus is 1.85 billion miles away from the sun. Voyager 2, the only spacecraft to visit this blue-green ice giant, attempted to find out what Uranus was made of in 1986, but the composition of the clouds was not certain.

So, how did these scientists confirm what Uranus smells like?

It was all thanks to a spectrograph, a sensitive instrument that can see light that is invisible to the human eye. The spectrograph helped scientists determine what gases were present in Uranus’s atmosphere.

Since both Jupiter and Saturn — other giants in our solar system — have ammonia cloud tops, the recent find of hydrogen sulfide on Uranus’ clouds is quite an interesting find.

However, it “wasn’t a complete surprise,” Grossman adds. “Observations from the 1990s showed hints of hydrogen sulfide lurking deeper in Uranus’ atmosphere. It just had not been ‘conclusively detected’ earlier.”

This recently found quality helps us better understand the details of our early solar system. The more we know about the exact makeup of these planets, the closer we get to figuring out how the solar system was formed.

It is very likely that hydrogen sulfide ice crystals were abundant deeper in the early solar system since hydrogen sulfide freezes at much colder temperatures in comparison with ammonia. This find suggests that “ice giants Uranus and Neptune were born farther from the sun than Jupiter and Saturn,” explains Grossman. These giants migrated closer to the sun after their formation. They were even farther away than they are now!

These giants “had access to different reservoirs of material back in the forming days of the solar system,” Fletcher says. He hopes to send a spacecraft to the ice giants to find out more about how these giants were formed. The team is working on pinpointing the birthplaces of Uranus and Neptune.