Astronomers, led by Cambridge University, have uncovered intriguing evidence suggesting potential biological activity on the distant exoplanet K2-18b. Located 124 light years away in the constellation of Leo, K2-18b is 8.6 times as massive and 2.6 times as large as Earth, orbiting within the habitable zone of a red dwarf star.
Using data from NASA’s James Webb Space Telescope (JWST), researchers identified the presence of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the planet’s atmosphere. On Earth, these compounds are almost exclusively produced by biological processes, particularly marine microorganisms like phytoplankton. This discovery marks the strongest evidence yet of possible life beyond our solar system, though scientists caution that the findings are not definitive proof of extraterrestrial life.
K2-18b has long been considered a candidate for habitability due to its atmospheric composition, which includes methane and carbon dioxide. These molecules, along with the newly detected DMS and DMDS, align with predictions for a “Hycean” planet—a type of world characterized by hydrogen-rich atmospheres and global oceans. Such environments could potentially support microbial life similar to that found in Earth’s oceans.
The detection of DMS and DMDS was achieved with a statistical confidence level of “three-sigma,” indicating a 99.7% likelihood that the signal is real. However, this falls short of the “five-sigma” threshold required for scientific confirmation. Researchers estimate that 16 to 24 hours of follow-up observations with JWST could help achieve the necessary confidence level.
Despite the excitement surrounding these findings, scientists remain cautious. Alternative explanations, such as non-biological processes like volcanic activity or hydrothermal vents, could account for the presence of these molecules. Further research is needed to rule out these possibilities and confirm the biological origin of the detected compounds.
The discovery has sparked renewed interest in the study of exoplanets and the search for life beyond Earth. If confirmed, the presence of life on K2-18b could revolutionize our understanding of the universe and suggest that life may be more common than previously thought.
