Cambridge researchers may have just brought us closer than ever to answering one of the biggest questions in science: Are we alone in the universe?
A new study of a planet using NASA’s James Webb Space Telescope (JWST) has identified what could be the strongest evidence of alien life to date. The planet in question is K2-18b, located 124 light years from Earth in the constellation Leo. It’s more than twice the size of Earth, and scientists now believe its atmosphere might contain molecules only known to be produced by living organisms—at least on our planet.
According to Professor Nikku Madhusudhan, who leads the research team at Cambridge University, signs of dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) were detected in the planet’s atmosphere. On Earth, these molecules are primarily released by marine phytoplankton and bacteria. That alone doesn’t confirm life—but it does move us closer to the possibility.
Madhusudhan told BBC News that the levels of DMS potentially found on K2-18b are thousands of times higher than on Earth. If those levels are real, it could suggest the planet is “teeming with life.” But he and the team are careful not to jump to conclusions. “This is not yet a discovery,” he said, noting the results still fall short of the scientific gold standard of five-sigma certainty. Right now, the data sits at three-sigma—99.7% confidence, impressive, but not definitive.
Still, this is a major step forward. When a weaker signal for DMS was first detected 18 months ago, many in the scientific community remained skeptical. The latest readings have significantly improved that confidence.
The James Webb telescope is powerful enough to detect chemical compositions in distant atmospheres by analyzing light as it filters through from a planet’s host star. K2-18b orbits a small red dwarf, and JWST’s instruments are revealing more about this planet with every pass.
While the current findings are being met with both excitement and caution, some astrophysicists are quick to point out the remaining unknowns. Dr. Catherine Heymans, Scotland’s Astronomer Royal, noted that even if these gases are confirmed, they could theoretically be the result of exotic geological activity rather than biology.
Others, including researchers at NASA’s Ames Research Center, suggest K2-18b could be a gas giant with no surface at all, which would rule out life as we know it. But Madhusudhan’s team counters that the absence of ammonia in the planet’s atmosphere hints at a liquid ocean, possibly capable of supporting microbial life.
For now, the scientific debate is far from over. The Cambridge team plans more JWST observations to boost the data quality over the next year or two. They’re also collaborating with other researchers to test whether DMS and DMDS can be formed through non-biological processes in lab conditions.
Even without confirmation, these findings mark a turning point. As Madhusudhan put it, “Decades from now, we may look back at this moment and recognize it as when the living universe came within reach.”
