Possible Signs of Life Detected on Distant Exoplanet K2-18b, Say Scientists

In a potentially groundbreaking development in the search for extraterrestrial life, scientists using NASA’s James Webb Space Telescope (JWST) have detected unusual chemical signatures in the atmosphere of a distant exoplanet known as K2-18b. The presence of two molecules — dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) — has sparked considerable excitement among researchers, as these compounds on Earth are primarily produced by marine microbes and certain bacteria.

“This is a transformational moment in the search for life beyond the solar system,” said Professor Nikku Madhusudhan, who led the study. “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.”

K2-18b is no ordinary planet. Approximately 8.6 times the mass of Earth, it belongs to a unique class of exoplanets called Hycean worlds — a combination of "hydrogen" and "ocean". These planets are believed to have deep, global oceans beneath hydrogen-rich atmospheres, potentially offering conditions that could support microbial life.

The detection of DMS and DMDS is particularly noteworthy because, according to current scientific understanding, these molecules are not easily produced through non-biological processes. In fact, Madhusudhan emphasized that the detected concentrations of these compounds are “thousands of times higher than their concentrations in Earth’s atmosphere,” suggesting the possibility of biological activity — though he cautioned that further investigation is necessary.

This isn’t the first time K2-18b has intrigued scientists. In September 2023, JWST detected water vapor in the planet’s atmosphere, along with methane and carbon dioxide — all of which are key markers in assessing a planet’s habitability.

“These new findings build upon earlier observations and give us even more reason to focus on this planet,” said Madhusudhan. “However, we need to be open and continue exploring other scenarios. At this stage, the most we can reasonably talk about is simple microbial life — likely similar to lifeforms found in Earth’s oceans.”

The research team is continuing to analyze the data and plans to carry out more targeted observations to determine the true origins of the detected molecules. While the presence of DMS and DMDS doesn’t confirm the existence of life, it represents a major step forward in astrobiology.

With the advanced capabilities of the James Webb Space Telescope, scientists are now better equipped than ever to study atmospheres of distant exoplanets. K2-18b, once a speck among thousands of planetary candidates, is now a prime target in the search for life beyond Earth.