The totality of water, whether liquid or ice, on a Terrestrial Class planet. In Gaian Type planets, a combination of the right mass, chemical composition, atmosphere, and the right distance from the Sun permits water to exist mainly as a liquid. The high heat capacity of this large volume of water (some 1 to 1.5 million cubic kilometres in a typical Eugaian world) buffers the planet surface from large temperature changes. In Europan Type worlds however, water exists mostly as ice (although sometimes also as slush or liquid).
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Development Notes
Text by M. Alan Kazlev
Initially published on 07 November 2001.