Water on exoplanets is mostly hidden deep inside

View larger. | Artist’s concept of K2-18b, a mini-Neptune or sub-Neptune exoplanet about 124 light-years from Earth. Observations from NASA’s Webb space telescope show it may have a deep global ocean beneath a hydrogen atmosphere. This is the exoplanet where the molecule dimethyl sulfide – a possible biosignature of life – was also tentatively detected by Webb, but not yet confirmed. A new study suggests water on exoplanets may be more common than expected, and most of that water may be on the inside...