NIRISS instrument on Webb maps an ultra-hot Jupiter's atmosphere

Astronomers have been studying an intriguing exoplanet, WASP-18 b, located 400 light-years away, since its discovery in 2009. The planet, an ultra-hot gas giant ten times more massive than Jupiter, has been mapped using data from the Canadian NIRISS instrument on the James Webb Space Telescope (JWST). The temperature map of the planet reveals a significant temperature change from the hottest point facing the star to the terminator, where the day and night sides meet. The observations suggest the presence of water vapor at various elevations in the planet's atmosphere, despite the extreme temperatures. The lack of east-west winds on the planet's dayside indicates the possibility of a strong magnetic field affecting wind patterns. The study sheds light on the formation and composition of unusual exoplanets like WASP-18 b, which differ from those in our own Solar System.