An ocean world (often known as ocean planet, although ocean moons are probably also a possibility) is a terrestrial planet whose surface is entirely or almost entirely covered by an ocean, usually of water.
Ocean planets can be formed when an ice-covered planet migrates inwards in its stellar system, with the ice melting as the planet gets closer to its star. The oceans on such planets could be hundreds of kilometers deep, much deeper than the oceans of Earth. The immense pressures in the lower regions of these oceans could lead to the formation of a mantle of exotic forms of ice. This ice would not necessarily be as cold as we understand ice. If the planet is close enough to its sun that the water's temperature reaches the boiling point, the water will become supercritical and lack a well-defined surface.
Alternatively, there might be ocean worlds whose ocean is not made out of water, but of another liquid such as ammonia or methane. Extremely hot planets might have molten metal and magma covering their surface. The (fictional) planet Solaris is perhaps the most unusual example of an ocean planet: its ocean is a living, sentient entity made of some kind of organic matrix. The (also fictional) astronomical object known as "The Waters" cannot be considered an ocean planet, as it is completely made of water, having no solid structure beneath. How this object is able to hold a spheric shape is still unknown.
The planet Venus was once considered a possible ocean world, until it was discovered that its surface temperature exceeds 460 °C (860 °F).
List of ocean worldsEdit
- Bestine IV
- Glacius II
- Ocean Planet
- Ojom (covered by oceans and glaciers, it could be considered a cross between an ocean world and an ice world)
- Oceana 8 (Presumably)