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Class A
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Class A 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:
Gothos
Life Forms: unknown
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Class B
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Class B 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:
Tholia
Life Forms: Tholians
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Class C
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Class C planets are small, typically
1 to 1/10 the mass of Earth and are in their sun's cold zone.
Temperatures hover just above absolute zero. Their atmospheres can be
either permanently frozen, or be extremely windy due to seasonal
temperature changes.
Example:
Pluto, Triton
Life Forms: unknown
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Class D
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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, asteroids, Regula
Life Forms: Fabrini, Vedala
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Class E
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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
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Class F
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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 still crystallizing.
Their atmospheres retain small amounts of toxic gases. As these
planets continue cooling they may become classes C, L, M or N.
Example:
Janus VI
Life Forms: Horta
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Class G
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Class G planets are typically about
the mass of Earth and are in their sun's hot zone. Their gravity
allows them to retain an atmosphere of heavy gases and metal vapors,
but due to strong solar radiation, their surfaces are very hot.
Example:
Medusa
Life Forms: Medusans
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Class H
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Class H planets are typically the
size of Earth and are in their sun's habitable zone. They are
extremely dry, possibly have oxygen-argon atmospheres and possibly be
bathed in lethal radiation, but can sometimes be habitable.
Example:
Rigel XII
Life Forms: Humanoid
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Class I
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Class I planets typically the mass of
Earth and are in their sun's outer habitable zone or cold zone. Due to
low solar radiation, their temperatures are extremely low. The
atmospheres can be permanently frozen.
Example:
Exo III, Efros
Life Forms: Efrosians
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Class J
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Class J planets (Gas Giants) 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
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Class K
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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
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Class L
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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:
Life Forms: Humanoid
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Class M
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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. With more water
they would be Class N.
Example:
Earth, Vulcan,Tychor IV
Life Forms: Humanoid
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Class N
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Class N 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
Life Forms: Humanoid
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Class S
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Class S planets (Gas Supergiants) 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
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Class U
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Class U planets (Gas Ultragiants) 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
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Class Y
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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
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