SB50: Poseidon Station :: Wiki - Planetary Classification

Class	Description	Age (bil. yrs)	Diameter (1,000 kms)	Atmosphere	Solar system zone	Life-forms	Examples
Class A	Geothermally active	0 to 2	1 to 10	hydrogen compounds	Ecosphere	?	Gothos
Class B	Geomorteus	0 to 10	1 to 10	extremely tenuous; negligible	Hot	?	Mercury
Class C	Geoinactive	2 to 10	1 to 10	frozen	Cold	?	Pluto, Psi 2000
Class D	Rocky moon/asteroid	2 to 10	0.1 to 4	negligible	Ecosphere		Regula, Luna
Class E	Geoplastic	0 to 2	10 to 15	hydrogen compounds	Ecosphere	carbon-cycle	Excalbia
Class F	Geometallic	1 to 3	10 to 15	hydrogen compounds	Ecosphere	silicon-based	Janus VI
Class G	Geocrystalline	3 to 4	10 to 15	carbon dioxide	Ecosphere	single-cell organisms	Delta Vega
Class H	Desert	4 to 10	8 to 15	Heavy gases, metal vapors	Ecosphere, cold	Drought-resistant	Nimbus III
Class I	Gas supergiant	2 to 10	140 to 1,000	varying zones	Ecosphere, Cold	?
Class J	Gas giant	2 to 10	50 to 140	Varying zones	Ecosphere, cold	Hydrocarbon-based	Jupiter, Saturn
Class K	Adaptable	4 to 10	5 to 10	Carbon dioxide	Ecosphere	Single-cell organisms	Mars, Mudd, Elba II
Class L	Marginal	4 to 10	10 to 15	Oxygen, argon, carbon dioxide	Ecosphere	Plants	Indri VIII
Class M	Terrestrial	3 to 10	10 to 15	Nitrogen, oxygen, argon, carbon dioxide	Ecosphere	Plants/humanoid	Earth, Vulcan, Bajor
Class N	Reducing	3 to 10	10 to 15	Carbon dioxide, sulfides	Hot	?	Venus
Class O	Pelagic	3 to 10	10 to 15	nitrogen, oxygen	Ecosphere, Cold	water-based	Azati Prime
Class P	Glaciated	3 to 10	10 to 15	nitrogen, oxygen	Cold	hardy plants/animals	Andoria, Exo III
Class Q	Variable	2 to 10	4 to 15	highly variable	All	highly variable	Genesis Planet, Remus
Class R	Rogue	2 to 10	4 to 15	negligible	*Outside solar system	non-photosynthetic	Dakala, Founders' homeworld
Class S	Small ultragiant	2 to 10	10,000 to 50,000	varying zones	Cold	?
Class T	Large ultragiant	2 to 10	50,000 to 120,000	varying zones	Cold	?
Class Y	"Demon"	2 to 10	10 to 15	Thermionic radiation	All	Mimetic	Silver Blood planet