TOI-199 b: a temperate Saturn with methane and no beaches

Published on May 24, 2026 | Translated from Spanish

A team of American astronomers has analyzed the atmosphere of TOI-199 b, an exoplanet the size of Saturn. Its temperature is only 77 °C, similar to a hot day on Earth. Using the James Webb telescope, they observed the planet via transit spectroscopy for 20 hours, detecting methane in its atmosphere. Although the climate is mild, scientists rule out that it is habitable.

exoplanet TOI-199 b transiting its host star, Saturn-sized planet with pale orange and blue bands, James Webb Space Telescope focused on the planet during transit, infrared light passing through the planetary atmosphere, spectral data lines showing methane absorption peaks on a monitor interface, telescope mirror segments reflecting starlight, astronomers in a control room analyzing real-time spectroscopy data, 20-hour observation timeline displayed on screens, technical illustration style, cinematic lighting, deep space background with distant stars, photorealistic engineering visualization

Twenty hours of observation for one chemical data point 🔬

The James Webb telescope used transit spectroscopy to capture the light from the yellow dwarf star, located more than 330 light-years away, as TOI-199 b passed in front of it. Over 20 hours, the instruments analyzed the atmospheric composition of the gas giant. The detection of methane is relevant because, in temperate worlds, its presence suggests active chemical processes. However, the planet's atmosphere does not contain the necessary elements for known life.

A Saturn with summer weather, but no pool 🌡️

At 77 °C, TOI-199 b has a climate that on Earth would be ideal for frying an egg on the sidewalk. But don't get your hopes up: there are no umbrellas or cocktails. It is a gas giant with no solid surface, so forget about planting an umbrella. Astronomers confirm that, although methane sounds like a cozy atmosphere, the planet is more like a pressure cooker than a tropical paradise.