HyperXeric Subtype

Very dry Earth-like worlds

Hyperxeric (crocus)
Image from Steve Bowers

Gaian Type planet in which water covers less than 10% of the surface, usually because most volatiles were lost during late stages of the planet's formation.

Precipitation is rare, even at the poles, and desert conditions prevail. The atmosphere will rarely be oxygen-rich, unless there is considerable remnant oxygen in the atmosphere from earlier stages of the planet's evolution.

Hyperxeric worlds fall into three main classes; warm or cool worlds with very little water on the surface, warm worlds with a significant reservoir of water in the atmosphere but where rain evaporates quickly, and cool worlds with few liquid oceans but significant ice or permafrost. Changes in climate can affect the ocean cover by allowing water to remain in liquid form for longer periods, allowing the oceans to grow; the reverse process may also occur.

Life will rarely be advanced in form, but highly specialised and hardy lifeforms may exist.
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Development Notes
Text by John M. Dollan in his Planet Classification List
Additional material by Steve Bowers
Initially published on 07 November 2001.