Scientists Discover Potentially Habitable Exoplanet K2-18b with Signs of Life-Supporting Molecules

April 18, 2025 — Cape Charles Mirror

Astronomers have identified a distant exoplanet, K2-18b, as one of the most promising candidates yet for hosting extraterrestrial life, following the discovery of carbon-based molecules in its atmosphere. Located 120 light-years from Earth in the constellation Leo, K2-18b is a “Hycean” world — a type of exoplanet believed to be covered in oceans beneath a hydrogen-rich atmosphere.

The planet, roughly 2.6 times the size of Earth and 8.6 times its mass, orbits a red dwarf star in the habitable zone, where temperatures could allow for liquid water to exist. Using the James Webb Space Telescope (JWST), scientists detected significant levels of carbon dioxide and methane in the atmosphere — molecules often associated with biological activity.

What has especially intrigued researchers is the potential detection of dimethyl sulfide (DMS), a molecule that on Earth is only known to be produced by life, primarily by phytoplankton in the oceans. While the evidence for DMS remains tentative, its presence could be a tantalizing clue that biological processes might be occurring on K2-18b.

“These findings mark a major step forward in our search for life beyond Earth,” said Dr. Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the study. “This is the first time we’ve detected possible biosignatures on a planet in the habitable zone with such clarity.”

K2-18b was originally discovered by NASA’s Kepler Space Telescope in 2015, but it wasn’t until the deployment of the JWST that scientists could study its atmosphere in detail. The telescope’s Near-Infrared Spectrograph (NIRSpec) enabled researchers to observe how starlight passed through the planet’s atmosphere, revealing the presence of gases.

Though K2-18b is far larger than Earth and more similar in size to Neptune, its composition is markedly different from gas giants. Its density suggests a rocky or water-rich interior, and its atmospheric pressure and temperature could support a liquid water ocean beneath the clouds.

Still, scientists caution that more data is needed before confirming whether life exists on K2-18b. Red dwarf stars, like the one it orbits, are known for their powerful solar flares, which could strip away atmospheres and pose challenges to habitability.

“Even if life isn’t present, understanding the atmospheric composition of K2-18b helps us narrow the conditions where life could exist,” said Dr. Lisa Kaltenegger, an astrophysicist at Cornell University not involved in the study. “It pushes the boundary of what we thought was possible.”

NASA and ESA scientists plan further observations of K2-18b using JWST and future missions such as the Habitable Worlds Observatory, which is expected to launch in the 2030s.

For now, K2-18b joins the short but growing list of exoplanets with environments that may resemble — or even surpass — Earth’s potential for hosting life.