Oceans on alien worlds are more common than you think, study reveals

Another quality to look for when searching for worlds with liquid water (and potentially life) is heat — needed to melt ice and drive chemical reactions. This planetary heat typically comes from two sources — radiogenic heat, driven by radioactive decay inside a planet, and tidal forces, the stretching of planets and moons as they orbit each other, the same force which creates tides on Earth.

This heat can be expelled from inside a planet though two means — continental drift, or volcanoes (including cyrovolcanoes which erupt with water rather than lava). The means by which this energy is released is important, potentially determining whether or not the planet is habitable.

Worlds with too much volcanism can turn into lava-covered infernos, while too little volcanic activity can prevent a world from developing a protective atmospheric layer. Worlds with moderate volcanism may be needed to support liquid water and a robust biological chemistry.