Uranus is home to clouds of hydrogen sulphide and the gas gives the distant planet a distinct “rotten eggs” aroma, a report has confirmed. The composition of Uranus’ atmosphere has been the source of long-running debate, but a team of international scientists now says it has evidence for hydrogen sulphide high in the ice giant’s cloud tops.
The findings were discovered using the Near-Infrared Integral Field Spectrometer (NIFS) instrument on the 8-metre Gemini North telescope, on Hawaii’s Mauna Kea summit, and published in the journal Nature. A team, led by Patrick Irwin from the University of Oxford, used the telescope to spectroscopically dissect the infrared light from the seventh planet in the solar system, pinpointing exactly how its atmosphere absorbs infrared light from the sun.
This “absorption-line data” allows the team to glean the composition of Uranus’ clouds. Scientists have hypothesised for decades about whether these clouds are made from hydrogen sulphide (H₂S) or ammonia (NH₃). “Now, thanks to improved hydrogen sulfide absorption-line data and the wonderful Gemini spectra, we have the fingerprint which caught the culprit,” said Irwin in a statement.