PLANETARY CLASSIFICATIONS

Planets' natural characteristics, such as age, mass and distance from their sun, place them in classes which have been assigned arbitrary alphabetic designation. A planet's distance from its sun, relative to that sun's luminosity, puts the planet in one of three thermal zones: hot, habitable or cold. A planet mass determines its internal heat generation and, in combination with its zone, its ability to hold an atmosphere. Some planets pass through distict stages as they form and age, which may put them in separate classes.

Class A	Geo-Thermal
	Class A are young planets, typically 1 to 1/10 the mass of Earth, and are in their sun's habitable or cold zones. Their surface is patially molten and the atmosphere is primarily hydrogen compounds. These planets cool to become Class C. Example: Gothos Life Forms: unknown

Class B	Geo-Morteus
	Class B planets are small, typically 1 to 1/10 the mass of Earth and are in their sun's hot zone. Due to a combination of weak gravity and strong solar radiation, their atmospheres are very tenuous, with few chemically active gases, and their surfaces are extremely hot. Example: Mercury Life Forms: unknown

Class C	Geo-Inactive
	Class C planets are small, typically 1 to 1/10 the mass of Earth and are in their sun's cold zone. Due to a combination of low solar radiation and little heat, their atmospheres are permanently frozen. Example: Pluto, Psi-2000 Life Forms: unknown

Class D	Asteroid / Moon
	Class D planets are small, typically 1 to 1/100 the mass of Earth, or less. Due to low gravity, they have lost their atmospheres. Their surfaces, directly exposed to radiation and meteor impact, are typically lifeless and heavily cratered. Example: Yonada, Regula Life Forms: Fabrini, Vedala

Class E	Geo-Plastic
	Class E planets are typically of about the mass of Earth and are in their sun's habitable zone. They are newly formed, and their surfaces are still molten. Their atmospheres still retain many hydrogen compounds, as well as reactive gases and rock vapors. These planets will cool, becoming Class F. Example: Excalbia Life Forms: Carbon-cycle

Class F	Geo-Metallic
	Class F planets are typically about the mass of Earth and are in their sun's habitable zone. They are younger than the Earth, and their surfaces are covered with volcanic eruptions due to a large molten core. Their atmospheres retain small amounts of toxic gases. As these planets continue cooling they become Class G. Example: Janus VI Life Forms: Horta

Class G	Geo-Crystaline
	Class G planets are typically about the mass of Earth and are in their sun's habitable zone. They are younger than Earth, and their surfaces are still crystalizing. As they continue to cool, these planet may become Class K, L, M, N, O, or P. Example: Delta Vega Life Forms: Primitive single-celled

Class H	Desert
	Class H planets are typically the size of Earth and can be found in all zones. They are extremely dry, possibly have oxygen-argon atmospheres and possibly be bathed in lethal radiation, but can sometimes be habitable. Example: Rigel XII, Nimbus III Life Forms: Humanoid

Class J	Gas Giant
	Class J planets are large, typically 10 to 100 times the mass of Earth, and are in their sun's cold zone. Low solar radiation and high gravity have allowed them to keep thick atmospheres of hydrogen and hydrogen compounds. Wind speeds up to 10,000 kph are possible. Core pressure may be high enough to generate heat. Example: Jupiter, Saturn Life Forms: unknown

Class K	Adaptable
	Class K planets are typically 1 to 1/10 the size of Earth, and are in their sun's habitable zone. They are unsuitable for humanoid life but can be adapted through the use of pressure domes and life support systems. Example: Mars, Elba II Penal Colony Life Forms: Primitive invertebrates

Class L	Marginal
	Class L planets are typically the size of Earth and are in their sun's habitable zone. They have oxygen-argon atmospheres and possibly high levels of carbon-dioxide. Humanoids may need respirators or tri-ox supplements to survive. They can possibly support life, but this is often limited to plant life. Example: Indrii VIII Life Forms: Humanoid

Class M	Terrestrial
	Class M planets are typically about the mass of Earth and are in their sun's habitable zone. Their atmospheres contain significant oxygen, liquid water is a significant surface feature, and lifeforms are generally abundant. Example: Earth, Vulcan, Bajor Life Forms: Humanoid

Class N	Reducing
	Class N planets are typically of about the mass of Earth and are in their sun's habitable zone. Due to the greenhouse effect of dense atmospheres heavy in carbon dioxide, their surfaces are very hot and water is found in vapor form, if present at all. Example: Venus Life Forms: Tholians

Class O	Pelagic
	Class O planets are typically about the mass of Earth and are in their sun's habitable zone. Their atmospheres contain significant oxygen, liquid water covers over 97 percent of the surface. Lifeforms are generally abundant. With less water they would be Class M. Example: Argo, Pacifica Life Forms: Humanoid

Class P	Glaciated
	Class P planets typically the mass of Earth and are in their sun's outer habitable zone. Due to low solar radiation, their temperatures are extremely low. The atmospheres can be permanently frozen. Example: Breen Homeworld, Exo III Life Forms: Humanoid

Class Q	Variable
	Class Q planets are typically the size of Earth and can be found in all zones. Surfaces range from molten to water and/or carbon dioxide ice, due to eccentric orbit or variable output of star Example: Genesis Life Forms: various

Class R	Rogue
	Class R planets are typically the size of Earth and are found in interstellar space or cometary halos. Their surface may be temperate due to geothermal venting. Atmosphere's consist of volcanic outgassing. Example: Dakala Life Forms: non-photosynthetic plants, animals

Class S	Gas Supergiant
	Class S planets are very large, typically 3,000 times the mass of the Earth, and are in their sun's cold zone. Low solar radiation and high gravity have allowed them to keep thick atmospheres of hydrogen and hydrogen compounds. High core temperatures cause them to radiate enough heat that liquid water is present. Example: Beta Pictoris B Life Forms: unknown

Class U	Gas Ultragiant
	Class U planets are very large, typically 10,000 times the mass of Earth, and are in their sun's cold zone. Low solar radiation and high gravity have allowed them to keep thick atmospheres of hydrogen and hydrogen compounds. High core temperatures cause them to radiate visible light. These are the largest possible planets, as more massive bodies generate enough core heat to initiate fusion reactions and become stars. Example: Beta Pictoris C Life Forms: unknown

Class Y	Demon Class
	Also known as Demon Planets, planets and planetoids of this class can be found in any of a star's zones. They are typically 10,000 to 15 thousand kilometers in diameter. Atmospheric conditions are often turbulent and saturated with poisonous chemicals and thermionic radiation. Surface temperatures can reach in excess of 500 Kelvins. It can be dangerous for a starship even to orbit such a planet. Example: Life Forms: mimetic