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The James Webb Space Telescope (JWST) has detected what some scientists are calling the strongest evidence yet of potential alien life on exoplanet K2-18 b. Researchers have identified atmospheric chemicals that, on Earth, are exclusively produced by living organisms.
K2-18 b was first discovered in 2015, orbiting an M-type star located 120 light-years from our planet. It’s a massive super Earth — 8.92 times heavier than our home world — and completes one orbit around its star every 32.9 days.
The groundbreaking research, published in The Astrophysical Journal Letters, reveals the presence of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the planet’s atmosphere. These aren’t just any chemicals — on Earth, they’re specifically created by living organisms, primarily microbial life like marine phytoplankton.
“There may be processes that we don’t know about that are producing these molecules,” explained Nikku Madhusudhan of the University of Cambridge, one of the study’s authors. “But I don’t think there is any known process that can explain this without biology.”
The scientific community isn’t entirely convinced.
Many experts are approaching these findings with significant caution. Dr. Nora Hanni, a chemist at the University of Berne’s Physics Institute, told The Guardian: “Life is one of the options, but it’s one among many. We would have to strictly rule out all the other options before claiming life.”
Even stronger skepticism comes from University of Michigan astrophysicist Ryan MacDonald, who doesn’t mince words about the discovery. “These new JWST observations do not offer convincing evidence that DMS or DMDS are present in K2-18 b’s atmosphere,” he told New Scientist. “We have a boy-who-cried-wolf situation for K2-18 b, where multiple previous three-sigma detections have completely vanished when subject to closer scrutiny.”
MacDonald emphasized that extraordinary claims require extraordinary evidence: “Any claim of life beyond Earth needs to be rigorously checked by other scientists, and unfortunately many previous exciting claims for K2-18 b haven’t withstood these independent checks.”
Madhusudhan, despite the skepticism, calls it “a revolutionary moment.”
“This is the strongest evidence to date for biological activity beyond the solar system,” he said. “We’re very cautious. We have to question ourselves both on whether the signal is real and what it means.”
The implications, if confirmed, would be staggering.
“Decades from now, we may look back at this point in time and recognize it was when the living universe came within reach,” Madhusudhan added. “This could be the tipping point, where suddenly the fundamental question of whether we’re alone in the universe is one we’re capable of answering.”
