Planetary Classification

A planet is a celestial body in orbit around a star or stellar remnants, that has sufficient mass for self-gravity and is nearly spherical in shape. A planet must not share its orbital region with other bodies of significant size (except for its own satellites), and must be below the threshold for thermonuclear fusion of deuterium.

If a celestial body meets those requirements, it is considered a planet; at that point, the planet is further classified by its atmosphere and surface conditions into one of twenty-two categories.

Contents
Class A - Geothermal	Class G - Geocrystalline	Class M - Terrestrial	Class S - Gas Supergiant
Class B - Geomorteus	Class H - Desert	Class N - Reducing	Class U - Gas Ultragiant
Class C - Geoinactive	Class I - Ice Giant (Uranian)	Class O - Pelagic	Class X - Chthonian
Class D - Dwarf	Class J - Gas Giant (Jovian)	Class P - Glaciated	Class Y - Demon
Class E - Geoplastic	Class K - Adaptable	Class Q - Variable
Class F - Geometallic	Class L - Marginal	Class R - Rogue

Class A - Geothermal

Class A planets are very small, barren worlds rife with volcanic activity. This activity traps carbon dioxide in the atmosphere and keeps temperatures on Class A planets very hot, no matter the location in a star system. When the volcanic activity ceases, the planet "dies" and is then considered a Class C planet.

AGE	0-2 billion years
DIAMETER	1,000 - 10,000 km
LOCATION	Hot Zone/Ecosphere/Cold Zone
SURFACE	Partially molten, very hot
ATMOSPHERE	Carbon dioxide, hydrogen
EVOLUTION	Cools to become Class C
LIFE FORMS	None
EXAMPLES	Gothos

Class B - Geomorteus

Class B planets are generally small worlds located within a star system's Hot Zone. Highly unsuited for humanoid life, Class B planets have thin atmospheres composed primarily of helium and sodium. The surface is molten and highly unstable; temperatures range from 450° in the daylight, to nearly -200° at night. No life forms have ever been observed on Class B planetoids.

AGE	0-10 billion years
DIAMETER	1,000 - 10,000 km
LOCATION	Hot Zone
SURFACE	Partially molten
ATMOSPHERE	Exremely Tenuous
EVOLUTION	N/A
LIFE FORMS	None
EXAMPLES	Mercury, Nebhilum

Class C - Geoinactive

When all volcanic activity on a Class A planet ceases, it is considered Class C. Essentially dead, these small worlds have cold, barren surfaces and possess no geological activity.

AGE	2-10 billion years
DIAMETER	1,000 - 10,000 km
LOCATION	Hot Zone/Ecosphere/Cold Zone
SURFACE	Barren
ATMOSPHERE	None
EVOLUTION	N/A
LIFE FORMS	None
EXAMPLES	Psi 2000

Class D - Dwarf

Also known as Plutonian objects, these tiny worlds are composed primarily of ice and are generally not considered true planets. Many moons and asteroids are considered Class D, as are the larger objects in a star system's Kuiper Belt. Most are not suitable for humanoid life, though many can be colonized via pressure domes.

AGE	2-10 billion years
DIAMETER	100 - 4,000 km
LOCATION	Hot Zone/Ecosphere/Cold Zone
SURFACE	Barren, Cratered
ATMOSPHERE	None or Very Tenuous
EVOLUTION	N/A
LIFE FORMS	None
EXAMPLES	Pluto, Ceres, Eredas-Il

Class E - Geoplastic

Class E 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. As the surface cools, the core and crust begin to harden, and the planet evolves into a Class F world.

AGE	2-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	Molten, high surface temp.
ATMOSPHERE	Hydrogen compounds
EVOLUTION	Cools to become Class F
LIFE FORMS	Carbon cycle
EXAMPLES	Excalbia

Class F - Geometallic

A Class E planet makes the transition to Class F once the crust and core have begun to harden. Volcanic activity is also commonplace on Class F worlds; the steam expelled from volcanic eruptions eventually condenses into water, giving rise to shallow seas in which simple bacteria thrive. When the planet's core is sufficiently cool, the volcanic activity ceases and the planet is considered Class G.

AGE	1-3 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	Volcanic, barren
ATMOSPHERE	Carbon dioxide, ammonia, methane
EVOLUTION	Cools to become Class G
LIFE FORMS	Bacteria
EXAMPLES	Janus IV

Class G - Geocrystalline

After the core of a Class F planet is sufficiently cool, volcanic activity lessens and the planet is considered Class G. Oxygen and nitrogen are present in some abundance in the atmosphere, giving rise to increasingly complex organisms such as primitive vegetation like algae, and animals similar to sponges and jellyfish. As the surface cools, a Class G planet can evolve into a Class H, K, L, M, N, O, or P class world.

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
EXAMPLES	Delta Vega

Class H - Desert

A planet is considered Class H if less than 20% of its surface is water. 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.

AGE	4-10 billion years
DIAMETER	8,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	Hot, arid; >20% surface water
ATMOSPHERE	Oxygen, nitrogen, argon, metals
EVOLUTION	n/a
LIFE FORMS	Drought-resistant plants/animals
EXAMPLES	Nimbus III, Ocampa

Class I - Ice Giant (Uranian)

Also known as Uranian planets, these gaseous giants have vastly different compositions from other giant worlds; the core is mostly rock and ice surrounded by a tenuous layers of methane, water, and ammonia. Additionally, the magnetic field is sharply inclined to the axis of rotation. Class I planets typically form on the fringe of a star system.

AGE	2-10 billion years
DIAMETER	30,000 - 100,000 km
LOCATION	Cold Zone
SURFACE	Rock, ice, methane, ammonia
ATMOSPHERE	Hydrogen, Helium
EVOLUTION	n/a
LIFE FORMS	None
EXAMPLES	Uranus, Neptune, Q'tahL

Class J - Gas Giant (Jovian)

Class J 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. They form in the Cold Zone of a star system, though typically much closer than Class I planets.

AGE	2-10 billion years
DIAMETER	50,000 - 500,000 km
LOCATION	Cold Zone
SURFACE	Liquid metallic Hydrogen
ATMOSPHERE	Hydrogen, Helium
EVOLUTION	n/a
LIFE FORMS	None
EXAMPLES	Jupiter, Saturn

Class K - Adaptable

Though similar in appearance to Class H worlds, Class K planets lack the robust atmosphere of their desert counterparts. Though rare, primitive single-celled organisms have been known to exist, though more complex life never evolves. Humanoid colonization is, however, possible through the use of pressure domes and in some cases, terraforming.

AGE	4-10 billion years
DIAMETER	5,000 - 10,000 km
LOCATION	Ecosphere
SURFACE	Barren, little surface water
ATMOSPHERE	Thin, mostly carbon dioxide
EVOLUTION	n/a
LIFE FORMS	Primitive single-cell organisms
EXAMPLES	Mars, Mudd

Class L - Marginal

Class L planets are typically rocky, forested worlds devoid of animal life. They are, however, well-suited for humanoid colonization and are prime candidates for terraforming. Water is typically scarce, and if less than 20% of the surface is covered in water, the planet is considered Class H.

AGE	4-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	Rocky, little surface water
ATMOSPHERE	Argon, oxygen, trace elements
EVOLUTION	n/a
LIFE FORMS	Limited to vegetation
EXAMPLES	Alarin III, Ciden II, Indri VII

Class M - Terrestrial

Class M planets are robust and varied worlds composed primarily of silicate rocks, and are highly suited for humanoid life. 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.

AGE	4-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	Abundant surface water, temperate climate
ATMOSPHERE	Nitrogen, oxygen, argon
EVOLUTION	n/a
LIFE FORMS	Vegetation, animal, & humanoid
EXAMPLES	Earth, Cardassia, Bajor, Vulcan

Class N - Reducing

Though frequently found in the Ecosphere, Class N planets are not conducive to life. The terrain is barren, with surface temperatures in excess of 500° and an atmospheric pressure more than 90 times that of a Class-M world. Additionally, the atmosphere is very dense and composed of carbon dioxide; water exists only in the form of thick,vaporous clouds that shroud most of the planet.

AGE	3-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	Barren, high temps.
ATMOSPHERE	carbon dioxide and sulfides
EVOLUTION	n/a
LIFE FORMS	None
EXAMPLES	Venus

Class O - Pelagic

Any planet with more than 80% of the surface covered in water is considered Class O. These worlds are usually very warm and possess vast cetacean populations in addition to tropical vegetation and animal life. Though rare, humanoid populations have also formed on Class O planets.

AGE	3-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	80% water, archipelagos
ATMOSPHERE	Nitrogen, oxygen, argon
EVOLUTION	n/a
LIFE FORMS	Cetacean, humanoid, animal
EXAMPLES	Azati Prime, Ka'Tula Prime, Zirat

Class P - Glaciated

Any planet whose surface is more than 80% frozen is considered Class P. These glaciated worlds are typically very cold, with temperatures rarely exceeding the freezing point. Though not prime conditions for life, hearty plants and animals are not uncommon, and some species, such as the Aenar and the Andorians, have evolved on Class P worlds.

AGE	3-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Ecosphere
SURFACE	80% frozen water, cold
ATMOSPHERE	Nitrogen, oxygen
EVOLUTION	n/a
LIFE FORMS	Vegitation, Animal, Humanoid
EXAMPLES	Andoria, Rura Penthe

Class Q - Variable

These rare planetoids typically develop with a highly eccentric orbit, or near stars with a variable output. As such, conditions on the planet's surface are widely varied. Deserts and rain forests exist within a few kilometers of each other, while glaciers can simultaneously lie very near the equator. Given the constant instability, is virtually impossible for life to exist on Class-Q worlds

AGE	2-10 billion years
DIAMETER	4,000 - 15,000 km
LOCATION	Hot Zone/Ecosphere/Cold Zone
SURFACE	Molten, frozen, jungle, etc
ATMOSPHERE	Very tenuous to very dense
EVOLUTION	n/a
LIFE FORMS	None
EXAMPLES	Genesis Planet

Class R - Rogue

A Class R planet usually forms within a star system, but at some point in its evolution, the planet is expelled, likely the result of a catastrophic asteroid impact. The shift radically changes the planet's evolution; many planets merely die, but geologically active planets can sustain a habitable surface via volcanic outgassing and geothermal venting.

AGE	2-10 billion years
DIAMETER	4,000 - 15,000 km
LOCATION	Interstellar Space
SURFACE	Temperate
ATMOSPHERE	Primarily Volcanic Outgassing
EVOLUTION	n/a
LIFE FORMS	Non-photosynthetic plants, animals
EXAMPLES	Founders' Homeworld (prior to 2371)

Class S - Gas Supergiant

Aside from their immense size, Class S planets are very similar to their Class J counterparts, with liquid metallic hydrogen cores surrounded by a hydrogen and helium atmosphere.

AGE	2-10 billion years
DIAMETER	500,000 - 100,000,000 km
LOCATION	Cold Zone
SURFACE	Liquid metallic hydrogen
ATMOSPHERE	Hydrogen and helium
EVOLUTION	n/a
LIFE FORMS	None
EXAMPLES	Tethe-Alla IV

Class U - Gas Ultragiant

Class U planets represent the upper limits of planetary masses. Most exist within a star system's Cold Zone and are very similar to Class S and J planets. However, Class T planets occasionally form within a star system's Hot Zone. If they are sufficiently massive (13 times more massive than Jupiter), deuterium ignites nuclear fusion within the core, and the planet becomes a red dwarf star, creating a binary star system.

AGE	2-10 billion years
DIAMETER	50,000,000 - 120,000,000 km
LOCATION	Hot Zone/Cold Zone
SURFACE	Liquid hydrogen, deuterium
ATMOSPHERE	Hydrogen and helium
EVOLUTION	Can evolve into red dwarf stars
LIFE FORMS	None
EXAMPLES	Diadem, Tethe-Alla V

Class X - Chthonian

Class X planets are the result of a failed Class T planet in a star system's Hot Zone. Instead of becoming a gas giant or red dwarf star, a Class X planet was stripped of its hydrogen/ helium atmosphere. The result is a small, barren world similar to a Class B planet, but with no atmosphere and an extremely dense, metal-rich core.

AGE	2-10 billion years
DIAMETER	1,000 - 10,000 km
LOCATION	Hot Zone
SURFACE	Barren, extremely hot
ATMOSPHERE	None
EVOLUTION	n/a
LIFE FORMS	None
EXAMPLES	Osirus

Class Y - Demon

Perhaps the most environmentally unfriendly planets in the galaxy, Class Y planets are toxic to life in every way imaginable. The atmosphere is saturated with toxic radiation, temperatures are extreme, and atmospheric storms are amongst the most severe in the galaxy, with winds in excess of 500 kph.

AGE	2-10 billion years
DIAMETER	10,000 - 15,000 km
LOCATION	Hot Zone
SURFACE	Barren, extremely hot
ATMOSPHERE	Turbulent, with toxic radiation
EVOLUTION	n/a
LIFE FORMS	Mimetic
EXAMPLES	Planet Hell (Delta Quadrant)

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