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.
