​Recent observations from the James Webb Space Telescope have unveiled potential signs of life on the exoplanet K2-18b, situated approximately 124 light-years away in the constellation Leo. Researchers from the University of Cambridge detected chemical compounds—dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)—in the planet’s atmosphere. On Earth, these molecules are predominantly produced by marine microorganisms, such as phytoplankton, making their presence on K2-18b particularly intriguing.

K2-18b is classified as a “Hycean” planet, characterized by a hydrogen-rich atmosphere and the potential for vast oceans. Its location within its star’s habitable zone suggests conditions that might support liquid water—a crucial ingredient for life as we know it. The detection of DMS and DMDS has led scientists to estimate a 99.7% probability that these molecules indicate biological activity.

Despite the promising findings, the scientific community urges caution. While the presence of these compounds is compelling, alternative non-biological processes could also account for their existence. Further observations and analyses are necessary to confirm the biological origin of these molecules. Achieving a higher confidence level, known as the “5-sigma” threshold, is essential for a definitive conclusion. ​