James Webb Detects Methane on TOI-199b at 175°F, Probing Rare Temperate Giant 330 Light-Years Away
Updated
Updated · India Today · May 22
James Webb Detects Methane on TOI-199b at 175°F, Probing Rare Temperate Giant 330 Light-Years Away
8 articles · Updated · India Today · May 22
TOI-199b, a gas giant more than 330 light-years from Earth, showed clear methane signatures in the first detailed atmospheric study of a temperate giant planet using JWST.
Transmission spectroscopy during a nearly 7-hour transit let astronomers read starlight filtered through the atmosphere after about 20 hours of baseline observations of the host star.
The planet orbits every 100 days and has an estimated atmospheric temperature near 175°F—mild by giant-planet standards—with hints of ammonia and carbon dioxide also appearing in the data.
Researchers said the rare middle-ground world helps test long-standing models of planetary chemistry and atmospheric evolution, expanding understanding of how planetary systems form beyond hot Jupiters and icy giants.
Methane was found on a temperate giant planet. Could its hidden moons hold the chemical building blocks for life?
Beyond this temperate giant, what other bizarre worlds has the Webb telescope revealed that defy scientific explanation?
Could a giant planet with mild temperatures rewrite the story of how planets, including our own, are born?
Methane Detected on Temperate Exoplanet TOI-199b: JWST Unveils New Frontier in Atmospheric Characterization
Overview
On May 21, 2026, scientists detected methane in the atmosphere of the temperate exoplanet TOI-199b, marking a major breakthrough in exoplanet research. By analyzing the planet’s atmospheric signature during its transit across its host star and comparing the observed spectra to a baseline, researchers found that TOI-199b’s atmosphere blocked specific wavelengths of starlight absorbed by methane. This direct observation confirmed theoretical models predicting methane in temperate gas-giant exoplanet atmospheres. The discovery opens up a new category of exoplanets for atmospheric study, showing that even temperate giant planets can reveal important chemical insights.