A recent study using data from the James Webb Space Telescope (JWST) has shed new light on the planet K2-18b, a sub-Neptune-sized world 124 light years away from Earth. While some scientists had suggested that K2-18b might host alien life due to signs of dimethyl sulfide and dimethyl disulfide in its atmosphere, others disputed these findings.
The new research, published on the arXiv preprint server, analyzed data from four recent JWST near-infrared transit observations combined with previous JWST and Hubble data. The results show that K2-18b has a water-rich interior, but no evidence of living organisms.
According to the study’s findings, K2-18b has a hydrogen-rich atmosphere containing methane and carbon dioxide, but limited evidence for ammonia and water vapor. However, the researchers found a robust detection of methane and carbon dioxide, which can only be explained by either a massive atmosphere or a small atmosphere overlaying a liquid-water ocean.
The study’s authors conclude that K2-18b has a water-rich interior, regardless of whether it hosts a liquid-water ocean. The absence of ammonia in the atmosphere is consistent with this scenario, but additional observations are needed to confirm this.
While the results indicate that there is no evidence of life on K2-18b, the planet remains an intriguing subject for scientists studying the emergence of liquid-water environments in non-Earth-like planets. Further characterization of its atmosphere and interior will be crucial to understanding the nature of its water content.
Source: https://phys.org/news/2025-07-planet-k2-18b-host-alien.html