In a groundbreaking development, astronomers utilizing the James Webb Space Telescope (JWST) have identified chemical compounds in the atmosphere of exoplanet K2-18 b that, on Earth, are exclusively associated with biological processes. Located approximately 124 light-years away in the constellation Leo, K2-18 b resides within the habitable zone of its red dwarf star, an area where conditions might allow for liquid water to exist.
The compounds detected—dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)—are known on Earth to be produced by marine microorganisms such as phytoplankton. The presence of these molecules in K2-18 b’s atmosphere was observed with a confidence level of 99.7%, suggesting a strong signal. However, scientists emphasize that while these findings are compelling, they do not constitute definitive evidence of life. Further observations and analyses are necessary to rule out non-biological sources for these compounds.
K2-18 b is categorized as a “Hycean” planet—a theoretical class of exoplanets characterized by a hydrogen-rich atmosphere and a vast ocean covering the surface. These conditions could potentially support microbial life, particularly in oceanic environments. The planet is about 8.6 times more massive than Earth and has a diameter approximately 2.6 times larger.
The detection was made using the transit method, where the telescope observes the light from the host star as the planet passes in front of it. This technique allows scientists to analyze the starlight filtered through the planet’s atmosphere, revealing its chemical composition.
While the discovery of DMS and DMDS is significant, researchers caution that alternative, non-biological processes could potentially produce these molecules. Further studies are planned to confirm the findings and explore other possible explanations.
This discovery marks a notable advancement in the field of astrobiology and the ongoing search for life beyond our solar system. The JWST’s capabilities have opened new avenues for detecting potential biosignatures on distant worlds, bringing scientists closer to answering the age-old question of whether we are alone in the universe.
For more detailed information, you can refer to the original study published in the Astrophysical Journal Letters.
