GUWAHATI: Tentative evidence suggesting the possibility of life on a distant exoplanet has been detected by a team of researchers from the University of Cambridge. The announcement was made on Friday, April 18, as the team delivered findings based on data collected by NASA's James Webb Space Telescope (JWST), indicating the presence of certain molecules in the atmosphere of K2-18b, a planet located 124 light years away.
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K2-18b is over twice the size of Earth and orbits a small red star. The team, led by Professor Nikku Madhusudhan, has identified potential traces of dimethyl sulphide (DMS) and dimethyl disulphide (DMDS)—gases on Earth that are produced only by marine microorganisms. The presence of these molecules, if confirmed, could suggest biological processes on the planet.
These findings mark the second time that signs of possible life-associated chemicals have been observed in K2-18b’s atmosphere, though the current evidence is stronger than before.
However, scientists have also stressed that the detection is not yet conclusive. The results presently meet a "three sigma" confidence level, meaning a 99.7% likelihood of accuracy. A more definitive "five sigma" result, which implies a 99.99999% certainty, is required for a formal scientific discovery.
According to reports, Professor Madhusudhan expressed optimism, stating that such confirmation could be possible within one or two years. He emphasised that, if proven, the discovery would suggest life might be common across the galaxy.
Despite the enthusiasm, scepticism remains within the scientific community. Independent experts, including Professor Catherine Heymans of Edinburgh University, noted that even with high certainty, non-biological explanations must be considered.
Meanwhile, the Cambridge team is currently collaborating with other researchers to explore whether the detected molecules can also be produced through non-living processes, as the debate extends to the structure of K2-18b itself.
Some researchers argue the planet could host a vast liquid ocean, supported by the absence of ammonia in its atmosphere. Others suggest it might be a mini gas giant with no surface or an ocean of molten rock, both of which would challenge the possibility of life.
The study has been published in The Astrophysical Journal Letters.