Planetary Classifications

The standard Federation system of planetary classification categorizes planets based on various factors such as atmospheric composition, surface temperature, vegetation and size. Each class is designated with a letter, for example, Class M (name based on the Vulcan terminology "Minshara class") is the most suitable for humanoid long-term habitation.

Planetary classes

Class	Description	Examples	Age (bill. yrs)	Diameter (1,000 kms)	Atmosphere	Solar system zone	Lifeforms
Class A	Geothermally active/partially molten	[Gothos]	0-2	1-10	Primarily hydrogen compounds	Ecosphere/Cold Zone	None
Class B	Geomorteus/partially molten/high surface temp.	Mercury	0-10	1-10	Extremely tenuous/few chemically active gases	Hot Zone	None
Class C	Geoinactive/low surface temp.	Pluto, Psi 2000	2-10	1-10	Frozen	Ecosphere/Cold Zone	None
Class D	Rocky asteroid or moon/barren and cratered	Regula, Luna	2-10	0.1-1	None or very tenuous	Ecosphere/Hot Zone/Cold Zone; primarily in orbit of larger bodies or in asteroid fields	None
Class E	Geoplastic/molten, high surface temp.	Excalbia I	0-2	10-15	Hydrogen compounds and reactive gases	Ecosphere	Carbon-cycle (Excalbian)
Class F	Geometallic/volcanic eruptions due to molten core	Janus VI	1-3	10-15	Hydrogen compounds	Ecosphere	Silicon-based (Horta)
Class G	Geocrystalline/still crystallizing	Delta Vega	3-4	10-15	Carbon dioxide, some toxic gases	Ecosphere	Primitive single-cell organisms
Class H	Desert/hot and arid, little or no surface water	Nimbus III, Rigel XII, Tau Cygna V	4-10	8-15	May contain heavy gases and metal vapors	Ecosphere/Hot Zone/Cold Zone	Drought- and radiation-resistant flora and fauna
Class I	Gas supergiant/tenuous surface comprised of gaseous hydrogen and hydrogen compounds/radiates heat	Q'tahL	2-10	140-1,000	Zones vary in temp., pressure, and composition; water vapor may be present	Cold Zone	Unknown
Class J	Gas giant/tenuous surface comprised of gaseous hydrogen and hydrogen compounds/radiates some heat	Jupiter, Saturn	2-10	50-140	Zones vary in temp., pressure, and composition	Cold Zone	Hydrocarbon-based
Class K	Adaptable/barren, little or no surface water	Mars, Mudd, Elba II	4-10	5-10	Thin, mostly carbon dioxide	Ecosphere	Primitive single-cell organisms; adaptable for humanoid colonization through pressure dome use
Class L	Marginal/rocky and barren, little surface water	Indri VIII, Fallon	4-10	10-15	Oxygen/argon, high concentration carbon dioxide	Ecosphere	Limited to plant life; suitable for humanoid colonization
Class M	Terrestrial/surface water abundant	Earth, Vulcan, Bajor, Cardassia Prime	3-10	10-15	Nitrogen, oxygen, trace elements	Ecosphere	Extensive vegetation, animals, humanoids
Class N	Reducing/high surface temp. due to greenhouse effect, water exists as vapor	Venus	3-10	10-15	Extremely dense, carbon dioxide and sulfides	Ecosphere	Unknown
Class O	Pelagic/liquid water covers 80% or more of surface	Pacifica	3-10	10-15	Nitrogen, oxygen, trace elements	Ecosphere	Aquatic flora, fauna, humanoids
Class P	Glaciated/water ice covers 80% or more of surface	Exo III	3-10	10-15	Nitrogen, oxygen, trace elements	Ecosphere	Hardy plants/animals/humanoids
Class Q	Variable/ranges from molten to water and/or carbon dioxide ice, due to eccentric orbit or variable output star	Genesis Planet	2-10	4-15	Ranges from tenuous to very dense	Hot Zone/Ecosphere/Cold Zone	Unknown
Class R	Rogue/may be temperate due to geothermal venting	Founders homeworld, Dakala	2-10	4-15	Primarily volcanic outgassing	Interstellar space/cometary halos	Non-photosynthetic flora, fauna
Class S	Small ultragiant/tenuous surface comprised of gaseous hydrogen and hydrogen compounds/radiates considerable heat	?	2-10	10,000-50,000	Zones vary in temp., pressure, and composition; water vapor may be present	Cold Zone	Unknown
Class T	Large ultragiant/tenuous surface comprised of gaseous hydrogen and hydrogen compounds/radiates considerable heat	Rigel VI	2-10	50,000-120,000	Zones vary in temp., pressure, and composition; water vapor may be present	Cold Zone	Unknown
Class Y	"Demon"/temperature can exceed 500 degrees Kelvin	"Silver Blood" Planet	2-10	10-15	Turbulent, saturated with toxic chemicals and thermionic radiation	Hot Zone/Ecosphere/Cold Zone	Mimetic

Reference(s)

• Mandel, Geoffrey. Star Trek Star Charts, New York: Pocket Books, 2002.