Astronomers have spotted a giant helium cloud billowing outward from a distant “super-puff” exoplanet, marking the first time NASA’s James Webb Space Telescope has captured such an atmospheric escape. WASP-107b, a low-density gas giant about 210 light-years away, appears to be losing its outer layers under intense stellar radiation. The ejected helium forms a massive exosphere about ten times the planet’s radius, which trails and even leads the planet in its orbit.

Helium Cloud Streams from WASP-107b According to a recent paper, using JWST, a McGill-led team has found a giant helium cloud that is leaking from WASP-107b. The gas cloud is an exosphere that extends to about ten times the planet’s radius and extends beyond the planet in its orbit.

Webb’s NIRISS infrared spectrograph found a helium signature, a slight dip in the star’s light that occurred about 1. 5 hours before the transit of WASP-107b. Researchers say this is the first time that the atmospheric escape of an exoplanet has been observed in the most direct way.

Super-puff planet WASP-107b WASP-107b is about the size of Jupiter (94% of Jupiter’s diameter), but only 12 percent as massive, giving it extremely low density. This “super-puff” world orbits very close to its star – Mercury is about seven times closer than the Sun – which exposes it to intense heating. Webb also detected high amounts of water vapor (but no methane) in the atmosphere, which supports the model that WASP-107b formed far away and then moved inward, where stellar heat is driving away its gases.