Webb telescope finds strongest signs of alien life yet on distant ‘Hycean’ world

Scientists may have found strongest evidence of life beyond Earth on exoplanet K2-18 b

In a discovery that could significantly advance the search for extraterrestrial life, scientists using the James Webb Space Telescope (JWST) have identified chemical markers in the atmosphere of a distant exoplanet that may be the strongest signs yet of biological activity beyond Earth. The planet in question, K2-18 b, orbits a red dwarf star 124 light-years away in the constellation Leo and has long intrigued astronomers due to its position within the so-called “habitable zone”—a region where temperatures could allow for liquid water on a planet’s surface.

The latest spectroscopic data captured by JWST indicate the presence of gases such as dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), compounds that on Earth are produced almost exclusively by biological processes—particularly by marine phytoplankton. These potential biosignatures, if confirmed, would mark the most compelling evidence to date of the possibility of alien life.

What is K2-18 b and why is it significant in the search for life?

K2-18 b belongs to a class of exoplanets known as “Hycean worlds”—planets larger than Earth but smaller than Neptune, which are believed to possess hydrogen-rich atmospheres and deep oceans. With a mass nearly nine times that of Earth, K2-18 b is not a terrestrial planet, but its potential to host a global ocean beneath its thick atmosphere has made it a prime candidate in the search for habitability beyond our solar system.

Unlike gas giants such as Jupiter, Hycean planets could theoretically host microbial life in their oceans, protected beneath dense atmospheres. The JWST’s infrared sensors offer a powerful tool to study these atmospheres by detecting the faintest molecular signatures as the planets transit in front of their host stars. It is through this method that DMS and DMDS were identified in the case of K2-18 b.

Could the detected chemicals truly signal alien life?

While the presence of DMS and related compounds is compelling, scientists caution that the findings are not yet conclusive proof of life. On Earth, DMS is almost entirely produced by biological processes, especially in marine environments. However, researchers acknowledge that unknown geochemical or photochemical reactions might also produce such compounds under different conditions.

Professor Nikku Madhusudhan, an astrophysicist at the University of Cambridge and lead investigator of the study, noted that the findings represent the “strongest evidence yet” of possible life beyond Earth. However, he also emphasized the need for further validation. The observations, made at a 99.7% confidence level, must be independently confirmed and subjected to peer review. Even then, caution is warranted in interpreting these signals as definitive evidence of biology.

How does this compare to previous exoplanet discoveries?

Previous missions like Kepler and Hubble identified thousands of exoplanets and even probed the atmospheres of some. However, JWST provides a step-change in capability. Its sensitivity in the infrared spectrum allows it to detect fainter signals, including a broader range of potential biosignature gases, at far greater distances than its predecessors.

In 2019, earlier observations from the Hubble Space Telescope hinted at the presence of water vapour in K2-18 b’s atmosphere. But this latest development goes much further by pointing to potential indicators of active biological processes. It marks the first time scientists have detected biosignature-like molecules on a planet that is both in the habitable zone and possesses key planetary characteristics—size, temperature, and composition—that align with the possibility of sustaining life.

What are the next steps in confirming life on K2-18 b?

The scientific community is now calling for extended observations of K2-18 b to confirm these early findings. Additional spectroscopy using JWST and eventually more advanced space telescopes could reveal a fuller picture of the planet’s atmospheric composition and dynamics. If consistent patterns of biological gas emissions are confirmed, it would represent a historic milestone in astrobiology.

Moreover, researchers will attempt to rule out false positives—signals that may arise from abiotic processes or observational artifacts. The key will lie in detecting multiple biosignature gases in specific ratios that are unlikely to be explained by anything other than biological activity. This multivariable approach is central to how scientists aim to build a compelling, testable case for life beyond Earth.

How would confirmation of alien life impact science and society?

While the notion of alien microbes may seem less dramatic than science fiction portrayals of intelligent beings, the implications of even microbial extraterrestrial life are enormous. It would suggest that life is not unique to Earth and that the conditions for life may arise in many parts of the universe.

This discovery could also reshape philosophical, religious, and scientific frameworks that have long considered Earth as the singular cradle of life. For the scientific community, it would validate decades of research in exoplanetary science, atmospheric chemistry, and the search for biosignatures. Funding priorities for space exploration could shift dramatically, with greater emphasis on probing Hycean and ocean worlds both inside and beyond our solar system.

Will future missions enhance our search for alien life?

In the coming decade, missions such as the European Space Agency’s Ariel and NASA’s Habitable Worlds Observatory are expected to deepen our understanding of exoplanet atmospheres. These missions will allow for longer and more detailed observations, expanding the list of target planets and refining detection techniques for biosignature gases.

The potential of AI-driven analysis, combined with next-generation instruments, could also enable real-time detection and classification of spectral signatures. Furthermore, closer-to-home missions like Europa Clipper and Dragonfly to Titan may yield insights into how life could arise in extreme environments, complementing findings from distant exoplanets.

While K2-18 b may remain beyond our reach for direct exploration, its atmosphere has now become a frontier for understanding the universality of life itself.