JWST Confirms Abundant Methane in Temperate Exoplanet Atmosphere via Detailed Spectroscopy
Summary: Astronomers used JWST to conduct detailed spectroscopy on a temperate exoplanet, confirming abundant atmospheric methane in a mild orbital environment (June 18, 2026).
According to NASA Space News, astronomers using NASA's James Webb Space Telescope (JWST) have obtained high-precision spectral observations of the exoplanet TOI-199b, confirming abundant methane in the atmosphere of a temperate giant planet for the first time. TOI-199b is roughly Saturn-sized but with a surface temperature closer to Earth's, placing it in the rare category of temperate giant planets.
While methane has long been detected in the cold giant planets of our own solar system — Jupiter, Saturn, Uranus, and Neptune — this is the first clear spectroscopic confirmation of methane in a temperate exoplanet atmosphere. JWST data also suggest possible traces of ammonia and carbon dioxide, offering a new reference point for studying giant planet atmospheric chemistry.
Temperate giant planets are exceptionally rare among known exoplanets, and few have been systematically studied with atmospheric spectroscopy. The TOI-199b results indicate compositional similarities to solar system giants, which could help refine atmospheric evolution models for exoplanets. The research team plans to continue observing similar targets with JWST to build a larger sample of data.