Rotten egg smell surrounds Uranus

The giant ice planet Uranus’s clouds smell like rotten eggs, data from the Gemini Observatory in Hawaii has revealed. The gas responsible for the odour, hydrogen sulfide, has been identified as the main component of the planet’s upper cloud layer.

For a long time, scientists were puzzled by Uranus’s continuum microwave adsorption spectrum – it was missing a component that atmospheric models couldn’t account for. Now a team of researchers from the UK, US and France have for the first time unambiguously identified the source of the planet’s spectrum disturbance as hydrogen sulfide.