Sub-Neptunes Could Forge Oceans from Within

A Nature study shows that many planets called sub-Neptunes can synthesize their own water deep inside, by hydrogen in their thick atmospheres reacting with molten rock to produce H2O. If common, this could make water much more widespread in the galaxy and not just delivered by comets or asteroids. However, the water forms interiorly and may not always become a surface ocean, and these results are experimental/theoretical, requiring integration into formation models and observational tests to assess implications for habitability.