James Webb Space Telescope Discovery

Webb Identifies Methane In an Exoplanet’s Atmosphere

Webb made a definitive detection of methane gas in the atmosphere of “warm Jupiter” WASP-80 b. Like the name suggests, the planet is similar in size to Jupiter, but with much warmer temperatures. At 163 light-years away, WASP-80 b is very far from us. But it orbits very close to its parent star, with a year of only 3 Earth-days! To study the planet’s atmosphere, Webb observed how the combined light from the star and the planet was affected as WASP-80 b moved in front of and behind its star. The science team then created spectra, or measurements of how much light was blocked or emitted by the planet's atmosphere at different wavelengths. These measurements inform scientists of the chemical composition of the exoplanet, as well as what that tells us about the planet’s birth, growth and evolution. Credit: NASA. The measured transit spectrum (top) and eclipse spectrum (bottom) of WASP-80 b from NIRCam’s slitless spectroscopy mode on NASA’s James Webb Space Telescope. In both spectra, there is clear evidence for absorption from water and methane whose contributions are indicated with colored contours. During a transit, the planet passes in front of the star, and in a transit spectrum, the presence of molecules makes the planet’s atmosphere block more light at certain colors, causing a deeper dimming at those wavelengths. During an eclipse, the planet passes behind the star, and in this eclipse spectrum, molecules absorb some of the planet’s emitted light at specific colors, leading to a smaller dip in brightness during the eclipse compared to a transit. Image Credit: BAERI/NASA/Taylor Bell.
An artist’s rendering of the warm exoplanet WASP-80 b whose color may appear bluish to human eyes due to the lack of high-altitude clouds and the presence of atmospheric methane identified by NASA’s James Webb Space Telescope, similar to the planets Uranus and Neptune in our own solar system. Image credit: NASA.