A new study has found that the atmosphere above the planet Uranus is full of a gas that makes the planet smell like rotten eggs.
Researchers have long wondered whether the clouds high up in Uranus’ sky dominated by ammonia ice, as is the case with gas giants Jupiter and Saturn, or by hydrogen sulfide ice, but lacked definitive evidence either way.
The study conducted by Patrick Irwin and his team has found that the clouds in Uranus’ upper atmosphere are composed largely of hydrogen sulfide, the gas that gives rotten eggs their distinctive odor.
The research team studied Uranus’ air using the Near-Infrared Integral Field Spectrometer (NIFS) instrument on the 26-foot (8 meters) Gemini North telescope in Hawaii. The NIFS instrument scrutinized reflected sunlight from a region immediately above the cloud layer in Uranus’s atmosphere and spotted the signature of hydrogen sulfide.
“If an unfortunate human were ever to descend through Uranus’ clouds, they would be met with very unpleasant and odiferous conditions,” study lead author Patrick Irwin, from the Oxford University in England, said in a statement. “Suffocation and exposure in the negative 200 degrees Celsius [minus 328 degrees Fahrenheit] atmosphere, made of mostly hydrogen, helium, and methane, would take its toll long before the smell.”
The researchers believe that the difference between the clouds of ice giants Neptune and Uranus and those of gas giants Jupiter and Saturn probably lie in the planets’ formation environments. It is expected that Uranus and Neptune coalesced much farther from the sun as compared to Jupiter and Saturn.
“During our solar system’s formation, the balance between nitrogen and sulfur — and hence ammonia and Uranus’s newly detected hydrogen sulfide — was determined by the temperature and location of [a] planet’s formation,” study co-author Leigh Fletcher, from the University of Leicester in England, said in the same statement.
The study finding was published online on April 23 in the journal Nature Astronomy.