Strong Hint of Life on K2-18b? Webb Spots Possible DMS
Possible Life on K2-18b? Webb Spots DMS
In April 2025, astronomers using the James Webb Space Telescope reported the strongest hints yet of possible biology on a world beyond our solar system. The exoplanet K2-18b shows signs of dimethyl sulfide (DMS)—a gas on Earth linked to marine life—alongside methane and carbon dioxide, consistent with a potential “Hycean” ocean world. Researchers stress this is not proof of life, but a promising lead that demands further observations.
What was detected—and why it matters
- DMS/DMDS signature: The team reports a spectral signal consistent with dimethyl sulfide (or its close cousin, dimethyl disulfide). On Earth, DMS is overwhelmingly produced by marine microbes.
- Context molecules: Earlier Webb observations also found methane (CH4) and carbon dioxide (CO2) on K2-18b, adding weight to the Hycean scenario: a hydrogen-rich atmosphere over deep oceans.
- Caution first: The authors emphasize the detection is tentative (about 3-sigma) and must be confirmed by more data and by ruling out non-biological chemistry.
Watch: lead author on the findings
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What is a Hycean world?
Hycean planets are sub-Neptunes with hydrogen-rich atmospheres that may cloak global oceans. Because they’re larger than Earth, their atmospheres are easier for telescopes to analyze—making them prime targets for early biosignature searches.
Why astronomers are still cautious
Some researchers note that the DMS/DMDS signal needs independent confirmation and that abiotic pathways have to be thoroughly excluded. Others point out that detecting one possible biosignature without a suite of supporting molecules can be misleading. Expect the community to probe K2-18b with additional Webb time and refined models before anyone makes stronger claims.
Background: methane & CO2 on K2-18b
Webb previously detected methane and CO2 in K2-18b’s atmosphere, with a notable lack of ammonia—features that initially put this world on the Hycean short list. Those results helped set the stage for the DMS search.
Balanced explainer: why the result is exciting—and why skepticism matters.
Key takeaways
- Most promising hint so far: Possible DMS/DMDS on K2-18b, a gas tied to biology on Earth.
- Hycean context: Methane + CO2 and atmospheric clues align with an ocean-world scenario.
- Not proof: The signal is tentative; more Webb data and cross-checks are essential.
Sources
Tags: Exoplanets, K2-18b, DMS, Biosignature, JWST, Hycean Worlds, Astrobiology
