Planet Classification

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Classifications

Class A - Geothermal

					Age: 0 - 2 billion years Diameter: 1,000 - 10,000 km Location: Ecosphere/Cold Zone Surface: Partially molten Atmosphere: Primarily hydrogen compounds Evolution: Cools to become Class C Life Forms: None Example: Gothos
Class A geoactive planets are generally small, barren worlds rife with volcanic activity. This activity traps carbon dioxide in the atmosphere, causing a greenhouse effect that keeps the temperature very hot, regardless of the planet's distance from the sun. When the volcanic activity eventually ceases, the planet 'dies' and usually becomes a Class C world - a few rare cases transform into Class Q geothermal planets. Until that happens, the toxic levels of carbon dioxide make this planet unsuitable to any known life form, though silicon-based life may be able to terraform it to their needs.

Class B - Geomorteus

					Age: 0 - 10 billion years Diameter: 1,000 - 10,000 km Location: Hot Zone Surface: Partially molten, high surface temperatures Atmosphere: Extremely tenuous, few chemically active gasses Evolution: None Life Forms: None Example: Mercury
Class B planets are small, mostly metallic rocky planetoids. This type of planet is usually very close to, and heated by, a parent star, featuring very little native geothermal energy. The atmosphere of these worlds is usually tenuous and features little or no chemically active particles. No lifeforms have ever been discovered on these planets. Due to the proximity to their star's destructive influence of most other materials, Class B worlds exhibit a highly iron-rich crust, with a magnetic core and no mantle.

Class C - Geoinactive

					Age: 2 - 10 billion years Diameter: 1,000 - 10,000 km Location: Ecosphere/Cold Zone Surface: Low surface temperature Atmosphere: Frozen Evolution: None Life Forms: None Example: Psi 2000
Class C worlds are a type of planet usually in the very late stages of development that has likely evolved from another class. Essentially dead, these small, rocky worlds are generally geothermally inactive and have a cold, barren surface. As their core cooled down, their rotation slowed and eventually their atmosphere dissipated. No life form as any use for these planets, although they do often possess rich mineral deposits from their volcanically-active past.

Class D - Dwarf Planetoids

					Age: 2 - 10 billion years Diameter: 100 - 1,000 km Location: Hot Zone/Ecosphere/Cold Zone; found primarily in orbit of larger planets or in asteroid fields/belts Surface: Barren and cratered Atmosphere: None or very tenuous Evolution: None Life Forms: None Example: Luna, Ceres
Class D planetoids are generally smaller asteroids or moons that are locked into the gravitational pull of a larger planetary body. Class D worlds are barren and rocky, often possessing no atmosphere usually composed of metals, predominantly nickel, iron, and silicate. Animal life is unable to form on D class planetoids. Depending on their proximity to a star, a D class may be hot and arid or cold and frozen. These planets can be made habitable by terraforming as was the case with Weytahn by the Andorians during the 2050s.

Class E - Geoplastic

					Age: 0 - 2 billion years Diameter: 10,000 - 15,000 km Location:Ecosphere Surface: Molten, high temperature Atmosphere: Hydrogen compounds and reactive gases Evolution: Cools to become Class F Life Forms: Carbon-cycle Example: Excalbia
Class E, or Primordial, planets represent the earliest stage in the evolution of a habitable planet. The core and crust is completely molten, making the planets susceptible to solar winds and radiation and subject to extremely high surface temperatures. The atmosphere is very thin, composed of hydrogen and helium.

Class F - Geometallic

					Age: 1 - 2 billion years Diameter: 10,000 - 15,000 km Location:Ecosphere Surface: Volcanic eruptions due to molten core Atmosphere: Hydrogen compounds Evolution: Surface cools to become Class G Life Forms: Primitive organic bacteria Example: Janus VI
Class F, or Developing, planets derive from the cooling and hardening of the crust in a Class E planet. Possesses a primarily silicate-based crust, although vulcanism is still rife. Water has begun to condense to form oceans, amid centuries of constant rainfall. The atmosphere and the life that may develop on the surface are intertwined; as the rich carbon dioxide atmosphere allows early photosynthetic life to flourish, these organisms flood the atmosphere with oxygen, pushing towards the next stage in its evolution.

Class G - Geocrystalline

					Age: 3 - 4 billion years Diameter: 10,000 - 15,000 km Location:Ecosphere Surface: Rocky, mostly barren Atmosphere: Carbon dioxide, oxygen, nitrogen Evolution: Cools to Class H, K, L, M, N O, P Life Forms: Vegetation, simple organisms Example: Delta Vega
Class G, or Primitive, planets derive from a Class F planet as its surface cools, volcanic activity lessens, and oxygen and nitrogen are more abundant in the atmosphere. The atmosphere is still primarily carbon dioxide released as the planet cools and crystallizes. Primitive vegetation like algae and simple animal lifeforms like sponges are able to take hold in oceans to supplement the planet's bacterial life. This is the most important step in the formation of most planets as multiple complex factors determine what class of planet will evolve next.

Class H - Desert

					Age: 4 - 10 billion years Diameter: 8,000 - 15,000 km Location: Hot Zone / Ecosphere / Cold Zone Surface: Hot and arid, little or no surface water Atmosphere: May contain heavy gases and metal vapors Evolution: None Life Forms: Drought- and radiation-resistant plants, animal life Example: Nimbus III, Ocampa
Rocky planets with primarily silicate crusts, Class H planets are true desert worlds. With less than 20% of its surface covered in surface water, and high levels of surface radiation, Class H planets are not conducive to complex ecosystems. Though many Class H worlds are covered in sand, it is not required to be considered a desert; it must, however, receive little in the way of precipitation. Drought-resistant plants and animals are common on Class H worlds, and many are inhabited by humanoid populations. Most Class H worlds are hot and arid, but conditions can vary greatly. Class M planets can be reduced to Class H through environmental damage.

Class I - Ice Giant

					Age: 2 - 10 billion years Diameter: 30,000 - 100,000 km Location: Cold Zone Surface: Rocky, with methane and ammonia ice Atmosphere: Hydrogen, helium, methane, ammonia, water Evolution: None Life Forms: None Example: Uranus, Neptune
Class I, or Uranian, planets are gaseous giants that have vastly different compositions from other giant worlds; the core is mostly rock and ice made of methane, water, and ammonia. Additionally, the magnetic field is sharply inclined to the axis of rotation. Unlike other gas giants, Class I planets almost exclusively form on the outer fringes of a young star system.

Class J - Gas Giant

					Age: 2 - 10 billion years Diameter: 50,000 - 140,000 km Location: Cold Zone Surface: Tenuous, composed of gaseous hydrogen and hydrogen compounds; radiates some heat Atmosphere: Zones vary in temperature, pressure and composition Evolution: None Life Forms: Hydrocarbon based Example: Jupiter, Saturn
Class J, or Jovian, planets are massive spheres of liquid and gaseous hydrogen, with small cores of metallic hydrogen. Their atmospheres are extremely turbulent, with wind speeds in the most severe storms reaching 600 kph. Many Class J planets also possess impressive ring systems, composed primarily of rock, dust, and ice, as well as many moons, some of which are often habitable. They form in the Cold Zone of a star system, though typically much closer than Class I planets.

Class K - Adaptable

					Age: 4 - 10 billion years Diameter: 5,000 - 10,000 km Location: Ecosphere Surface: Barren, little surface water Atmosphere: Thin, mostly carbon dioxide Evolution: Class L if extensively terraformed Life Forms: Primitive single-cell organisms Example: Mars, Mudd
Class K planets are essentially dead terrestrial planets, with a primarily silicate crust, rich mineral deposits, and no magnetic field. The atmosphere is thin, predominantly carbon dioxide, and retains little heat, leading to a frigid desert landscape. Nonetheless, there can be some weather systems in a Class K atmosphere, and vulcanism can occur. Water and/or carbon dioxide ice may be found at the poles. Class K surfaces are barren, often cold, and cannot support animal life as there is commonly no liquid water or too little to sustain vegetation. Class K environments can develop from the evolution of Class G, or through the long deterioration of classes G, L or M. Their weak magnetic fields allow large quantities of solar radiation to reach the surface and heat to escape back into space. Colonization is possible by the use of pressure domes or monumental terraforming efforts.

Class L - Marginal

					Age: 4 - 10 billion years Diameter: 10,000 - 15,000 km Location: Ecosphere Surface: Rocky and barren, little surface water Atmosphere: Oxygen / argon, high concentration of carbon dioxide Evolution: Class M with limited terraforming Life Forms: Limited to vegetation Example: Mars, Mudd
Similar to Class M planets, Class L planets are on the borderline of life-bearing environments. Typically rocky, silicate-crust planets, Class L worlds are commonly arid, but in some cases display oceans or tundra. Surface temperature varies considerably, and the atmosphere is thinner than on a Class M world, with high levels of argon, carbon dioxide, and often other toxic gases. Radiation levels are potentially dangerous. Class L environments may feature basic ecosystems, normally only with plant life. They may, however, be colonized by humanoid life, and are excellent targets for terraforming.

Class M - Terrestrial

					Age: 3 - 10 billion years Diameter: 10,000 - 15,000 km Location: Ecosphere Surface: Water abundant Atmosphere: Nitrogen, oxygen, trace elements Evolution: None Life Forms: Extensive vegetation, animal life, humanoids Example: Earth, Bajor, Cardassia
Class M, or Minshara-class, planets are the most stable type for most humanoid habitation. To be considered Class M, between 20% and 80% of the surface must be covered in water; it must have a breathable oxygen-nitrogen atmosphere and temperate climate. With silicate crusts, those with rotating iron cores can display strong magnetic fields. Rich nitrogen-oxygen atmospheres with some carbon dioxide, water vapor, and trace gases are ideal for the development of varied, complex biospheres. Class M planets feature high surface and atmospheric water content, essential for organic life. Surface conditions can vary considerably across the globe, from tundra, to temperate, to desert environments. Class M worlds can vary widely in visual appearance. Class M is divided into subtypes dependent on surface water levels and other features, and these can vary over the course of a planet's lifespan.

Planetary Zone Classification Map

Planetary Zone Classifications Map

Credits

Descriptions, Icons, and Map created by and used with permission from Schmidt. Information originally created/gathered for the USS Fitzgerald, Star Trek Roleplaying Game. Information concerning granting of permission can be obtained via your CO or TFCO. Should specific topic be archived, please contact the Administrator.