Alien Life on K2-18 b? Webb Telescope Finds Biosignatures on Distant Planet
A giant planet 124 light-years away, K2-18 b, may hold the strongest evidence yet of extraterrestrial life, astronomers say.
The James Webb Space Telescope detected potential signs of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)—compounds on Earth produced only by living organisms.
While not definitive proof, the discovery brings humanity closer to answering whether we are alone in the universe.
“This is the strongest evidence to date for biological activity beyond the solar system,” said Prof. Nikku Madhusudhan of the University of Cambridge, who led the study. “Decades from now, we may look back at this point in time and recognize it was when the living universe came within reach.”
K2-18 b, nearly nine times Earth’s mass, orbits a cool red dwarf in the habitable zone. In 2019, Hubble detected water vapor, but follow-up observations suggested methane instead. Madhusudhan’s team now argues the planet could host a vast ocean—though this remains debated.
“The signal came through strong and clear,” Madhusudhan said.
“If we can detect these molecules on habitable planets, this is the first time we’ve been able to do that as a species… it’s mind-boggling.”
Published in The Astrophysical Journal Letters, the findings show DMS/DMDS levels thousands of times higher than Earth’s, with a 0.3% chance of being a false detection. Still, Madhusudhan cautions: “There may be processes we don’t know about… but I don’t think any known process can explain this without biology.”
Skeptics argue alternative explanations exist, such as comet impacts, volcanoes, or exotic chemistry. “Life is one of the options, but it’s one among many,” said Dr. Nora Hänni, who found DMS on a lifeless comet.
Others, like Dr. Jo Barstow, remain cautious: “For such a profound discovery, the burden of proof must be very high. I don’t think this crosses that threshold.”
While K2-18 b is too distant for direct study, Madhusudhan believes indirect methods suffice: “In astronomy, the question is never about going there… We’re trying to establish if the laws of biology are universal.”
Whether this marks a breakthrough or a false alarm, the search continues—with K2-18 b now a prime candidate in the hunt for alien life.
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