In an exciting new discovery, researchers using the James Webb Space Telescope (JWST) have detected a possible chemical signature in the atmosphere of a distant exoplanet called K2-18 b. This signature points to the presence of dimethyl sulfide (DMS), a molecule that on Earth is only produced by living organisms. The discovery was announced in a paper accepted for publication in The Astrophysical Journal and has sparked significant interest due to its potential implications for the search for extraterrestrial life.

K2-18 b is a sub-Neptune exoplanet, roughly 8.6 times the mass of Earth, located 124 light-years away from us in the constellation Leo. The planet has gained attention because it orbits within its star’s habitable zone, the region where conditions could allow liquid water to exist—one of the key ingredients for life. Previous studies have already detected water vapor in its atmosphere, and scientists now believe K2-18 b could be a Hycean world, meaning it may be covered by a vast ocean and surrounded by a hydrogen-rich atmosphere.

This latest discovery by JWST adds another intriguing layer to the planet’s profile. Among the molecules detected, the presence of methane and carbon dioxide was confirmed, but the most exciting finding was the potential detection of DMS. However, researchers are urging caution as this detection is still classified as tentative. Further observations are needed to confirm whether DMS is definitively present.

DMS is particularly interesting because, on Earth, it is produced by marine organisms, such as phytoplankton. If DMS is truly present in K2-18 b’s atmosphere, it could hint at biological processes occurring on the planet, raising the tantalizing possibility of life beyond Earth. However, the researchers stress that this finding is far from conclusive. As lead author Nikku Madhusudhan, a professor of astrophysics at the University of Cambridge, explains, “Aliens” is not the first conclusion scientists jump to. All other possible explanations must be ruled out first.

This isn’t the first time a potential signature of life has been detected on another planet. A few years ago, researchers thought they had found phosphine in the atmosphere of Venus—a molecule that could indicate biological activity. But follow-up studies debunked that claim, showing the complexity of identifying potential biosignatures.

Even if the DMS signal turns out to be a false alarm, the capability of JWST is remarkable. Madhusudhan highlights that the telescope was able to detect these chemical signatures with just two observations of K2-18 b. In comparison, similar observations using the Hubble Space Telescope would have required multiple years to achieve the same precision. JWST’s extended wavelength range and high sensitivity have opened up new possibilities for studying the atmospheres of exoplanets, giving researchers more tools to identify potential signs of life.

While it may take up to a year for follow-up data to confirm the presence of DMS, this discovery marks a promising step in the quest to find life on a habitable exoplanet. Whether this potential signal turns out to be a breakthrough or a false flag, it demonstrates just how far our technology has come in exploring distant worlds. For now, all eyes are on K2-18 b, and the wait for answers continues.