K2-18b

Scientists in University of Cambridge have published their analysis of the data collected by James Webb telescope, presenting the results showing likely dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS) signal in the atmosphere of an exoplanet K2-18b. This is thought to be a hycean world, which is supposed to have large liquid water ocean with hydrogen atmosphere but not all scientists agree even that. There were preliminary results suggesting DMS in the atmosphere published earlier, but this later analysis by the group presented more evidence claiming to have strengthened the earlier findings to 3 sigma levels.

DMS on Earth is produced by microbes like phytoplankton, and the researchers consider it in the atmosphere of K2-18b as a potential sign of large amounts of life in the ocean of K2-18b. However, the possibility of some exotic chemistry occurring in extraterrestrial conditions (different gravity, temperature, availability of component chemicals, space chemistry, etc) has not been excluded and may explain the signal, in which case it would be abiogenic. Besides, collecting spectroscopy signals from faraway planets (in this case about 120 light years away) is difficult, and more data is needed to verify the DMS/DMDS signal instead of some other chemical with similar spectrum at 5 sigma certainty.

In any case, an interesting possibility and worth noting, just in case.