James Webb Space Telescope

Using the James Webb Space Telescope (JWST), astronomers have discovered that a "puffy" planet is asymmetric, meaning there is a significant difference between one side of the atmosphere and the other.

The extrasolar planet or "exoplanet" in question is WASP-107 b, which orbits an orange star smaller than the sun located around 210 light-years away. Discovered in 2017, WASP-107 b is 94% the size of Jupiter but only has 10% of the mass of the solar system gas giant. This means it is one of the least dense exoplanets ever discovered, far "puffier" than expected.

Earlier this year, scientists determined this is likely the result of the interior of WASP-107 b being much hotter than predicted, and the planet is also thought to possess a rocky core that is larger than what was previously modeled. These strange characteristics were explained by a scarcity of methane in its atmosphere. Now, scientists have another WASP-107 b mystery to solve.

The curious asymmetry of WASP-107 b presents astronomers with a conundrum. "This is the first time the east-west asymmetry of any exoplanet has ever been observed from space as it transits its star," Matthew Murphy, a graduate student at the University of Arizona's Steward Observatory, said in a statement.

Murphy and colleagues studied WASP-107 by recording light from its host star as it passed through the atmosphere of the planet as it crossed or "transited" the face of its star. "A transit is when a planet passes in front of its star — like the moon does during a solar eclipse," Murphy said, adding that "observations made from space have a lot of different advantages versus observations that are made from the ground."

WASP-107 b orbits its star at a distance of around 5 million miles, or about 6% of the distance between Earth and the sun. This means that the planet completes an orbit in around five Earth days. In addition, the exoplanet is tidally locked to its star. This results in one side, the "dayside," permanently facing the star, while the other, the "nightside," faces out to space in perpetuity...............

https://www.space.com/exoplanet-inflated-asymmetry-james-webb-space-telescope