The hypothesis of the oceanic planet K2-18b has been disproved

Observations from the James Webb Space Telescope have detected carbon dioxide and methane, indicating that K2-18b may be covered by an ocean of magma. However, in the new paper, astronomers say that the data actually indicates that the planet is a minineptune.

According to the scientists, thermochemical processes in the deep atmosphere can explain the presence of methane and carbon dioxide detected by JWST, while kinetics in the deep atmosphere, such as upwelling, lead to the absence of ammonia and carbon monoxide. While the hykean hypothesis remains viable, it requires a biological source of methane, which presents too complex and implausible an explanation for the authors.