Planetary Classes

Class A

Gothos (TOS 18)

Geothermal

Age	0-2 billion years
Diameter	1,000-10,000km
Location	Ecosphere/Cold Zone
Surface	Partially molten
Atmosphere	Primarily hydrogen compounds
Evolution	Cools to become Class C
Lifeforms	None
Example	Gothos

 

Class B

Geomorteus

Age	0-10 billion years
Diameter	1,000-10,000km
Location	Hot Zone
Surface	Partially molten, high surface temperature
Atmosphere	Extremely tenuous, few chemically active gases
Lifeforms	None
Example	Mercury

 

Class C

Geoinactive

Age	2-10 billion years
Diameter	1,000-10,000km
Location	Ecosphere/Cold Zone
Surface	Low surface temperature
Atmosphere	Frozen
Lifeforms	None
Example	Pluto, Psi 2000

 

Class D

Moon (Sol IIIa) (ENT 96)

Asteroid/Moon

Age	2-10 billion years
Diameter	100-1,000km
Location	Hot Zone/Ecosphere/Cold Zone; found primarily in orbit of larger planets or in asteroid fields
Surface	Barren and cratered
Atmosphere	None or very tenuous
Lifeforms	None
Example	Moon (Sol IIIa), Lunar V (Bajor VIIe)

 

Class E

Geoplastic

Age	0-2 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Molten, high surface temperature
Atmosphere	Hydrogen compounds and reactive gases
Evolution	Cools to become Class F
Lifeforms	Carbon cycle (Excalbians)
Example	Excalbia

 

Class F

Geometallic

Age	1-3 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Volcanic eruptions due to molten core
Atmosphere	Hydrogen compounds
Evolution	Cools to become Class G
Lifeforms	Silicon-based (Horta)
Example	Janus VI

 

Class G

Delta Vega (TOS 01)

Geocrystalline

Age	3-4 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Still crystallizing
Atmosphere	Carbon dioxide, some toxic gases
Evolution	Cools to become Class K, L, M, N, O, or P
Lifeforms	Primitive single-celled organisms
Example	Delta Vega

 

Class H

Desert

Age	4-10 billion years
Diameter	10,000-15,000km
Location	Hot Zone/Ecosphere/Cold Zone
Surface	Hot and arid, little or no surface water
Atmosphere	May contain heavy gases and metal vapors
Lifeforms	Drought- and radiation-resistant plants, animal life
Example	Rigel XII, Tau Cygna V

 

Class I

Gas Supergiant

Age	2-10 billion years
Diameter	140,000-10 million km
Location	Cold Zone
Surface	Tenuous, comprised of gaseous hydrogen and hydrogen compounds; radiates heat
Atmosphere	Zones vary in temperature, pressure, and composition; water vapor may be present
Lifeforms	Unknown
Example	Q'tahl

 

Class J

Jupiter (TNG 101-102)

Gas Giant

Age	2-10 billion years
Diameter	50,000-140,000km
Location	Cold Zone
Surface	Tenuous, comprised of gaseous hydrogen and hydrogen compounds; radiates some heat
Atmosphere	Zones vary in temperature, pressure, and composition
Lifeforms	Hydrocarbon-based (Jovian)
Example	Jupiter, Saturn

 

Class K

Mars (STSC)

Adaptable

Age	4-10 billion years
Diameter	5,000-10,000km
Location	Ecosphere
Surface	Barren, little or no surface water
Atmosphere	Thin, mostly carbon dioxide
Lifeforms	Primitive single-celled organisms; adaptable for humanoid colonization through the use of pressure domes
Example	Mars

 

Class L

Marginal

Age	4-10 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Rocky and barren, little surface water
Atmosphere	Oxygen/argon, high concentration of carbon dioxide
Lifeforms	Limited to plant life; suitable for humanoid colonization
Example	Indri VIII

 

Class M

Earth (Star Trek)

Terrestrial / Minshara class

Age	3-10 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Surface water abundant; if water or ice covers more than 80% of surface, planet is considered Class O or P
Atmosphere	Nitrogen, oxygen, trace elements
Lifeforms	Extensive vegetation, animal life, humanoids
Example	Earth, Vulcan

 

Class N

Reducing

Age	3-10 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	High surface temperature due to greenhouse effect; water exists only as vapor
Atmosphere	Extremely dense, carbon dioxide and sulfides
Lifeforms	Unknown
Example	Venus

 

Class O

Pelagic

Age	3-10 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Liquid water covers 80% or more of surface area
Atmosphere	Nitrogen, oxygen, trace elements
Lifeforms	Aquatic vegetation, animal life, humanoids
Example	Argo

 

Class P

Glaciated

Age	3-10 billion years
Diameter	10,000-15,000km
Location	Ecosphere
Surface	Water ice covers 80% or more of surface area
Atmosphere	Nitrogen, oxygen, trace elements
Lifeforms	Hardy vegetation, animal life, humanoids
Example	Exo III

 

Class Q

Variable

Age	2-10 billion years
Diameter	4,000-15,000km
Location	Hot Zone/Ecosphere/Cold Zone
Surface	Ranges from molten to water and/or carbon dioxide ice, due to eccentric orbit or variable output of star
Atmosphere	Ranges from tenuous to very dense
Example	Genesis Planet

 

Class R

Rogue

Age	2-10 billion years
Diameter	4,000-15,000km
Location	Interstellar space, cometary halos
Surface	May be temperate due to geothermal venting
Atmosphere	Primarily volcanic outgassing
Lifeforms	Non-photosynthetic plants, animal life
Example	Dakala

 

Classes S-T

Ultragiant

Age	2-10 billion years
Diameter	10-50 million km (Class S) 50-120 million km (Class T)
Location	Cold Zone
Surface	Tenuous, composed of gaseous hydrogen and hydrogen compounds; radiates considerable heat
Atmosphere	Zones vary in temperature, pressure, and composition; water vapor may be present
Lifeforms	Unknown

 

Class Y

Demon

Age	2-10 billion years
Diameter	10,000-50,000km
Location	Hot Zone/Ecosphere/Cold Zone
Surface	Temperature can exceed 500°K
Atmosphere	Turbulent, saturated with toxic chemicals and thermionic radiation
Lifeforms	Crystalline, Mimetic
Example	Tholia, Demon Planet (Delta Quadrant)