Scientists Detect Possible Signs of Life on Alien Planet K2-18 b

• Apr 17, 2025

In a groundbreaking discovery, scientists using the James Webb Space Telescope (JWST) have found the strongest evidence yet of potential life beyond our solar system. Researchers have detected chemical signatures of gases in the atmosphere of an exoplanet, K2-18 b, that are usually produced by biological processes on Earth.

The two gases, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), are produced by living organisms on Earth, primarily by microorganisms like marine phytoplankton. The presence of these gases in the atmosphere of K2-18 b raises the possibility that microbial life could be thriving on the planet. However, scientists are cautious, stating that this does not confirm the existence of life but suggests a possible biosignature—an indicator of biological activity.

Lead author Nikku Madhusudhan, an astrophysicist at the University of Cambridge, called this a "transformational moment" in the search for life beyond our solar system. He emphasized that while this discovery marks a significant step forward in observational astrobiology, further observations are needed to confirm the findings.

K2-18 b is a "hycean" world—an exoplanet believed to be covered by a liquid water ocean, with a hydrogen-rich atmosphere. The planet is 8.6 times as massive as Earth and has a diameter 2.6 times larger. It orbits a red dwarf star about 124 light-years from Earth in the constellation Leo. This location places it in the "habitable zone" where liquid water could exist, making it an ideal candidate for the search for life.

Previously, JWST observations had detected methane and carbon dioxide in K2-18 b’s atmosphere, suggesting the planet could support life. The latest findings of DMS and DMDS provide even stronger evidence of biological processes at work. These gases were found at concentrations much higher than on Earth, making it unlikely that their presence could be explained by non-biological processes.

However, the scientific community remains cautious. Christopher Glein, a scientist not involved in the study, emphasized the need for further testing and analysis to confirm the data's accuracy. Madhusudhan also warned that additional observations and studies are required to rule out alternative explanations for the presence of these gases.

While the discovery of potential biosignatures on K2-18 b is exciting, scientists urge caution before claiming evidence of life. Further studies are needed to ensure the findings are robust and to eliminate the possibility of a statistical anomaly.