Those 'signs of life' everyone’s talking about on that famous planet? Yeah, it might just be some boring sulfur smog.
March 20, 2026
Original Paper
Organosulfur Chemistry on sub-Neptunes: Implications for hazes and biosignatures
arXiv · 2603.18923
The Takeaway
Earlier reports suggested the planet K2-18b might harbor life because of specific gases detected in its atmosphere by the James Webb Space Telescope. This study shows that natural chemical reactions involving sulfur and sunlight can mimic those 'biosignatures,' providing a much simpler, non-biological explanation.
From the abstract
The organosulfur biosignature gases dimethylsulfide (DMS) and dimethlydisulfide (DMDS) have recently been claimed to be present in the atmosphere of sub-Neptune exoplanet K2-18b, leading to the suggestion of possible extraterrestrial life. Abiotic formation pathways for DMS and DMDS in reducing atmospheres have also been proposed, raising concern over the use of DMS and DMDS as biosignature gases more generally. In this paper we independently test and contrast the proposed abiotic formation path