Washington DC [US], April 17 : A team led by Indian-origin astrophysicist Dr. Nikku Madhusudhan has revealed what may be the most compelling evidence yet of extraterrestrial life — not in our solar system, but on a distant exoplanet named K2-18b, located 120 light-years from Earth, as reported by The New York Times.
The findings, based on in-depth atmospheric analysis, point to the presence of dimethyl sulfide — a molecule on Earth that is produced solely by living organisms like marine algae.
“It’s in no one’s interest to prematurely claim we’ve detected life,” said Madhusudhan, a University of Cambridge astronomer, during a press briefing on Tuesday. “But the best explanation for our data is that K2-18b may be covered in a warm ocean teeming with life.” He called the discovery a “revolutionary moment,” marking the first time humanity may have detected biosignatures on a potentially habitable exoplanet.
Published in The Astrophysical Journal Letters on Wednesday, the study has ignited cautious optimism in the scientific community. While researchers are intrigued by the implications, many are urging restraint in interpretation. “It’s a hint, but not a confirmation,” said Stephen Schmidt, a planetary scientist at Johns Hopkins University.
Discovered by Canadian astronomers in 2017, K2-18b is classified as a sub-Neptune — a category of planets larger than Earth but smaller than Neptune. These planets, though common in other solar systems, have no known counterpart near Earth.
In 2021, Dr. Madhusudhan and his team theorized that such planets could possess deep oceans under thick hydrogen-rich atmospheres. They coined the term “Hycean” planets — blending “hydrogen” and “ocean.” The launch of the James Webb Space Telescope (JWST) in December 2021 allowed them to test their theories.
As K2-18b passed in front of its star, Webb captured starlight filtered through its atmosphere. Analysis of the light revealed various gases, including methane and hydrogen — consistent with the Hycean model. Intriguingly, scientists also detected dimethyl sulfide (DMS), a potential biosignature gas.
Last year, the team observed the exoplanet again using a different JWST instrument, confirming an even stronger signal of DMS, as well as dimethyl disulfide — another molecule potentially linked to life. “It’s a shock to the system,” Madhusudhan said, referring to the persistence of the chemical signature.
The level of DMS detected is far greater than on Earth, suggesting the presence of active biological processes in the exoplanet’s oceans — if the atmosphere is indeed similar to Earth’s.
However, not all scientists agree on K2-18b’s habitability. A recent paper by planetary scientist Christopher Glein suggests it might instead be a massive rocky planet with a scorching, uninhabitable atmosphere.
Experts caution that much more research is needed — including lab simulations to understand how DMS behaves under Hycean conditions.
“This is just the beginning of understanding these strange new worlds,” said Matthew Nixon, a planetary scientist at the University of Maryland.
Future JWST observations will provide more data, but concerns are growing over continued funding. Reports suggest the Trump administration may slash NASA’s science budget, potentially halting new astrobiology missions. “If that happens, the search for life elsewhere could come to a standstill,” warned astrobiologist Joshua Krissansen-Totton.
Despite the cautious tone of most researchers, excitement remains high. “I’m not screaming ‘aliens’ yet,” said Cornell’s Nikole Lewis. “But I always reserve the right to.”