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Scientists have reported what they describe as the strongest evidence yet of potential life beyond our solar system, after detecting chemical compounds in the atmosphere of a distant exoplanet that, on Earth, are produced almost exclusively by living organisms.
Using the James Webb Space Telescope, researchers identified traces of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) on K2-18b — a planet 124 light-years away and about 2.5 times the size of Earth. The telescope analyses the planet’s atmosphere by observing starlight passing through it from its small red sun.
On Earth, DMS and DMDS are primarily produced by microbial life such as marine phytoplankton. While scientists acknowledge that unknown chemical processes could explain the presence of these molecules, their detection on K2-18b — which orbits within its star’s habitable zone — is being hailed as a promising sign.
“This is the strongest evidence yet there is possibly life out there,” said Professor Nikku Madhusudhan of Cambridge University’s Institute of Astronomy. “We may be able to confirm this signal within one to two years. The levels we’ve estimated are thousands of times higher than on Earth. If they are linked to life, this planet could be teeming with it.”
The discovery has led to speculation that K2-18b may even host an ocean. However, Dr. David Clements, an astrophysicist at Imperial College London who was not involved in the research, urged caution: “While this is a step in the right direction, it’s not yet a definitive detection of DMS or DMDS.”
Earlier analyses of Webb data using different statistical models found no strong evidence of the compounds. Madhusudhan’s team later reanalysed the data, concluding that DMS remains the most plausible explanation. Meanwhile, researchers at Caltech found that while models including DMS fit the observations slightly better, they still fall short of the statistical certainty required for confirmation.
The findings have ignited excitement among astronomers, underscoring both the promise of detecting life on exoplanets and the difficulties of proving it.
