LONDON, UK— Scientists using the James Webb Space Telescope (JWST) have identified the strongest evidence yet of possible life beyond our solar system.
By analyzing the atmosphere of an exoplanet named K2-18 b, they detected two gases — dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) — that are typically produced on Earth by biological processes, specifically by marine phytoplankton.
These gases have never been observed in the atmosphere of an exoplanet before, and their presence raises the exciting possibility that K2-18 b could harbor microbial life.
However, researchers caution that these are not definitive signs of life but rather potential biosignatures — indicators of biological processes.
More observations and analysis are required to confirm these findings, and scientists remain cautious about jumping to conclusions.
“This is a transformational moment in the search for life beyond the solar system,” said astrophysicist Nikku Madhusudhan of the University of Cambridge, the study’s lead author. “We have demonstrated that it is possible to detect biosignatures in potentially habitable planets with current facilities. We have entered the era of observational astrobiology.”
K2-18 b, located about 124 light-years away in the constellation Leo, is a “hycean world” — a type of exoplanet covered by liquid water oceans and with a hydrogen-rich atmosphere.
The planet, which is 8.6 times as massive as Earth and about 2.6 times larger in diameter, orbits in the habitable zone of a red dwarf star, where liquid water could exist on its surface.
Earlier observations from JWST had already detected methane and carbon dioxide in the planet’s atmosphere, and the new discovery of DMS and DMDS further supports the hypothesis that K2-18 b could be a potential home for life.
While Madhusudhan expressed excitement over the findings, he emphasized the need for caution, urging further research to confirm the presence of microbial life.
The presence of DMS and DMDS at atmospheric concentrations much higher than those found on Earth — thousands of times higher — is a key finding.
“This cannot be explained without biological activity based on current scientific knowledge,” Madhusudhan stated.
The gases’ high concentrations at more than 10 parts per million suggest the possibility of biological processes on the planet, but the research team remains open to other explanations.
Despite the excitement, experts in the field advise careful interpretation of the results.
Christopher Glein, a principal scientist at the Southwest Research Institute, called the findings “tantalizing” but stressed the need for independent verification and additional analysis.
“We must be very careful to test the data as thoroughly as possible,” Glein said.
K2-18 b belongs to the “sub-Neptune” class of planets, with a size between Earth and Neptune.
Scientists used the “transit method” to analyze the planet’s atmosphere, a technique that involves observing the light from the star as the planet passes in front of it.
By measuring the starlight that passes through the planet’s atmosphere, scientists can identify the gases present and determine their composition.
Madhusudhan and his team hope to confirm the results by repeating the observations two to three times, ensuring that the signal is robust and statistically significant.
While the discovery is an exciting development in the search for extraterrestrial life, the researchers stressed that it remains speculative at this stage.
“The ‘Holy Grail’ of exoplanet science is to find evidence of life on an Earth-like planet beyond our solar system,” Madhusudhan said. “We may be within just a few years of detecting possible alien life on a hycean world, but we must remain cautious and continue exploring all possibilities.”
