WASP-107b, located 210 light-years away and orbiting very close to its star, is truly a strange world. It is nearly as large as Jupiter in size but has only one-tenth of Jupiter's mass, placing it in the class of extremely light "super-puff" planets.
Observations from the James Webb Space Telescope (JWST) revealed that the atmosphere of this "super-puff" planet is literally evaporating into space. The escaping helium gas cloud extends to a region five times the planet's diameter and trails ahead along its orbital path.
Gas giants like Jupiter usually form far from their stars. Scientists believe WASP-107b also formed far from its star but gradually migrated to a dangerously close orbit due to other forces in the system.
As it approached its star, extreme heat began breaking apart the planet's outer layers. JWST observations confirmed the scale of this destruction: the helium cloud in the atmosphere was detected about 1.5 hours before the planet itself passed in front of the star, showing that the atmosphere was escaping the planet's gravity.
The elements in the planet's atmosphere support this migration story. A high abundance of oxygen proves it did not form close to the star, while traces of water, carbon monoxide, and carbon dioxide were also detected.
One element, however, was surprising: methane, which chemical calculations predicted should be abundant, was absent. Researchers suggest the star's intense heat pushes methane-poor gases from the planet's depths to the surface, rendering methane virtually invisible.
While Earth loses a small portion of its atmosphere, WASP-107b is experiencing extreme atmospheric escape. Scientists hope that studying this unusual world will help them understand how planets like Venus lost their atmospheres over time.
