JWST May Have Found Strongest Evidence of Life on Exoplanet K2-18b

While cautious about the findings, astronomers detected traces of a chemical that, on Earth, is produced by phytoplankton.

By Paul Smaglik
Apr 17, 2025 8:30 PMApr 17, 2025 8:27 PM
Artist's impression of the exoplanet K2-18b
Astronomers have detected the most promising signs yet of a possible biosignature outside the solar system, although they remain cautious. Using data from the James Webb Space Telescope (JWST), the astronomers, led by the University of Cambridge, have detected the chemical fingerprints of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS), in the atmosphere of the exoplanet K2-18b, which orbits its star in the habitable zone. (Image Credit: A. Smith, N. Madhusudhan (University of Cambridge))

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Astronomers have spotted a small, but potentially significant biosignature outside the solar system — but so far remain cautious about declaring it a conclusive sign of life, because there is a slight, but important, statistical probability that the observance occurred by chance.

The biosignature contains what appears to be traces of one or two chemicals that, on Earth, are only produced by living microorganisms, such as marine phytoplankton. Astronomers using the James Webb Space Telescope (JWST) detected dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS), in the atmosphere of the exoplanet K2-18b, they report in The Astrophysical Journal Letters.

Exoplanet Demonstrating Signs of Life

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