Hycean planet

A hycean planet (/ˈhaɪʃən/ HY-shən) is a hypothetical type of exoplanet that features a liquid water ocean underneath a hydrogen-rich atmosphere.

[1] The presence of extraterrestrial liquid water makes hycean planets regarded as promising candidates for planetary habitability.

Hycean planets are thought to be common around red dwarf stars, and are considered to be a promising place to search for life beyond Earth.

[6] Their water-rich compositions imply that they can have larger sizes than comparable non-hycean planets, thus making detection of biosignatures easier.

[3][8] In 2023, the JWST investigated K2-18b and found evidence for both a hycean atmosphere and the presence of dimethyl sulfide ─ a potential biosignature.

If the planet orbits a sun-like star at one Astronomical unit (AU), the temperature would be so high that the oceans would boil and water would become vapor.

[11] Hycean planets may be capable of supporting extraterrestrial life, despite their properties differing drastically from Earth's.