Webb finds sulfur in exoplanet atmosphere, revealing planet formation secrets
NASA's James Webb Space Telescope just detected a sulfur-bearing molecule (hydrogen sulfide) in the atmosphere of HR 8799 c, one of the giant exoplanets orbiting star HR 8799, about 133 light-years away, and found sulfur-bearing signatures that are likely present in some of the system's other inner giants.
The findings do not claim a first-ever detection of sulfur beyond the Solar System, and they back up the idea that these planets formed by building rocky cores before pulling in gas—kind of like how Jupiter did.
Discovery gives fresh look at how giant planets come together
Sulfur isn't usually floating around as a gas when planets are forming, so finding it means these worlds probably started with solid cores.
The team also noticed these planets have more heavy elements than their star, which tells us even massive planets (some five to 10 times bigger than Jupiter!) can form far from their star.
As lead researcher Jean-Baptiste Ruffio put it, this discovery gives us a fresh look at how giant planets come together—even in places we didn't expect.