Scientists found a potential sign of life on a distant planet – an astronomer explains why many are still skeptical

An illustration of the exoplanet K2-18b, which some research suggests may be covered by deep oceans. NASA, ESA, CSA, Joseph Olmsted (STScI)

A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, they had found evidence for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms.

In April 2024, the James Webb Space Telescope stared at the host star of the planet K2-18b for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules to the telescope.