In a breakthrough that could reshape the scientific search for extraterrestrial life, astronomers using the James Webb Space Telescope (JWST) have detected chemical compounds in the atmosphere of a distant exoplanet that, on Earth, are absolutely grown by biological processes.
The planet, famous as K2-18 b, orbits a red dwarf star roughly 124 light-year distance from the constellation Leo. Researchers report that the planet’s atmosphere contains dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)—organic molecules that, on Earth, are primarily emitted by marine microorganisms such as phytoplankton.
The discovery, detailed in a study published in The Astrophysical Journal Letters, was led by Dr. Nikku Madhusudhan, an astrophysicist at the University of Cambridge’s Institute of Astronomy.
“This is a ground breaking moment in the search for life beyond the solar system,” Madhusudhan said in a statement. “We have showed that it is possible to determine biosignatures in possibly livable earths with existing facilities. We have entered the period of observational astrobiology.”
Despite the significance of the findings, Madhusudhan and his team caution that this does not constitute confirmation of extraterrestrial life. The detected gases are considered biosignatures—indicators that suggest biological activity might be present—but the team emphasized the need for repeated observations and further theoretical modeling to rule out abiotic (non-biological) sources of these chemicals.
Currently, the presence of DMS and/or DMDS has been confirmed at a 99.7% confidence level, or 3σ—statistically strong, but below the 5σ threshold generally accepted for scientific certainty.
“Firstly, we essential to recurrence the notes two to three times to make certain the sign we are seeing is more visible,” Madhusudhan said. “Second, we need more theoretical and experimental studies to ensure there is no plausible abiotic mechanism to explain these molecules under the observed conditions.”
A Hycean World
K2-18 b, around 2.6 times the diameter of Earth and 8.6 times more enormous, falls into the class of sub-Neptune exoplanets. It exist in within the star’s inhabitable area—the orbital expanse where temperatures may allow fluid water to exist on the planetary surface.
The planet is believed to be a so-called “Hycean world”—a class of hypothetical exoplanets featuring global oceans beneath hydrogen-rich atmospheres. These conditions could support microbial life similar to that found in Earth’s oceans, albeit under potentially warmer and higher-pressure environments.
Previous JWST explanations had already branded methane and carbon dioxide in K2-18 b’s atmosphere, proposing the attendance of carbon-based chemistry. The addition of DMS and DMDS braces the case for biological activity,all though hesitations prevail.
“The mere scenario that presently describes all the data found so far… is one where K2-18 b is a Hycean world teeming with life,” said Madhusudhan. “However, we need to be open and continue exploring other scenarios.”
Scientific Reaction and Next Steps
The JWST used the transit spectroscopy method to analyze K2-18 b’s atmosphere. As the planet passes in front of its host star, a fraction of starlight filters through the atmosphere, allowing scientists to identify gases based on their unique spectral signatures.
The newly detected compounds were identified using an alternative JWST instrument operating in a different wavelength range than previous observations, strengthening the case for their presence. Still, researchers acknowledge the need for independent verification and additional data.
Humanity’s Oldest Question
For thousands of years, men have deliberated whether we are unaccompanied in the universe. The finding of DMS and DMDS on a aloof planet now brings that interrogation into the dominion of empirical science. Madhusudhan trusts that the decisive uncovering of alien life may be within reach—maybe even within a few years.
“It is in no one’s curiosity to assertion early that we have detected life,” he said. With more than 5,800 exoplanets discovered since the 1990s, K2-18 b may now be the most promising candidate for the search for extraterrestrial life. As technology and observational capabilities improve, scientists remain hopeful that future missions will either confirm or refute these intriguing hints from a distant world.
