Astronomers’ recent claims of potential alien life on exoplanet K2-18b have raised doubts, with several studies finding insufficient evidence to support the discovery. The planet, 124 light years away in the Leo constellation, is considered a prime suspect due to its distance from its star and potential for liquid water.
The detection of chemicals dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) on K2-18b sparked hopes that humanity might soon discover extraterrestrial life. However, two researchers have re-analyzed the data and found that there is not enough evidence to confirm a biosignature.
The team, led by Cambridge University’s Nikku Madhusudhan, initially detected the chemicals at a three-sigma level of statistical significance, indicating a 1 in 1,000 chance that it was a fluke. However, when other researchers deployed different statistical models, claims of a potential biosignature detection vanished.
“We’re not saying the planet definitely doesn’t have DMS,” said Luis Welbanks, an Arizona State University researcher who re-analyzed the data. “But we need more observations to confirm our findings.”
Welbanks and his colleague Matthew Nixon, Maryland University researcher, expanded their analysis to 90 possible chemicals that could explain the signals detected by the James Webb Space Telescope. They found that over 50 received a “hit,” but Welbanks questioned whether detecting many possibilities actually means anything.
Madhusudhan welcomed the debate, saying it’s essential for the scientific method. He released his own preprint study, which expanded the number of chemicals even further to 650, including diethyl sulfide and methyl acrylonitrile.
Despite the controversy, many researchers believe that space telescopes could one day collect enough evidence to identify alien life from afar. “We’re the closest we’ve ever been,” Welbanks said, but emphasized the need for reliable methods and rigorous analysis.
Source: https://phys.org/news/2025-05-alien-life-dim-emerge-exoplanet.html