CLASS A -- (Geothermal)

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 B -- (Geomorteus)

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: -- Mercury

CLASS C -- (Geoinactive)

Diameter: -- 1,000 - 10,000 km
Location: -- Ecosphere / Cold Zone
Surface: -- Low surface temperature
Atmosphere: -- None
Evolution: -- n/a
Life Forms: -- None
Example: -- Pluto, Psi 2000

CLASS D -- (Asteroid/Moon)

Diameter: -- 100 - 1,000 km
Location: -- Hot Zone / Ecosohere / Cold Zone; found primarily in orbit of larger planets or in asteroid fields
Surface: -- Barren and cratered
Atmosphere: -- None or very tenuous
Evolution: -- n/a
Life Forms: -- None
Example: -- Sol III1, Bajor VIIe

CLASS E --(Geoplastic)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Molten, high surface temperature
Atmosphere: -- Hydrogen compounds and reactive gases
Evolution: -- Cools to become Class F
Life Forms: -- Carbon-cycle (Excaliban)
Example: -- Excalbia

CLASS F -- (Geometallic)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Volcanic eruptions due to molten core
Atmosphere: -- Hydrogen compounds
Evolution: -- Cools to become Class G
Life Forms: -- Silicon-based (Horta)
Example: -- Janus IV

CLASS G -- (Geocrystaline)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Still crystallizing
Atmosphere: -- Carbon Dioxide, some toxic gases
Evolution: -- Cools to become Class K, L, M, N, O or PC
Life Forms: -- Primitive single-celled organisms
Example: -- Delta Vega

CLASS H -- (Desert)

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: -- n/a
Life Forms: -- Drought- and radiation-resistant plants, animal life
Example: -- Rigel XII, Tau Cygna V

CLASS I -- (Gas Supergiant)

Diameter: -- 140,000 - 10,000,000 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
Evolution: -- n/a
Life Forms: -- Unknown
Example: -- Q'tahL

CLASS J -- (Gas Giant)

Diameter: -- 50,000 - 100,000 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
Evolution: -- n/a
Life Forms: -- Hydro-Carbon based (Jovian)
Example: -- Jupiter, Saturn

CLASS K -- (Adaptable)

Diameter: -- 5,000 - 10,000 km
Location: -- Ecosphere
Surface: -- Barren, little or no surface water
Atmosphere: -- Thin, mostly carbon dioxide
Evolution: -- n/a
Life Forms: -- Primitive single-celled organisms; adaptable for humanoid colonization through the use of pressure domes
Example: -- Mars, Mudd

CLASS L -- (Marginal)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Rocky and barren, little surface water
Atmosphere: -- Oxygen / Argon, high concentration of carbon dioxide
Evolution: -- n/a
Life Forms: -- Limited to plant life; suitable for humanoid colonization
Example: -- Indri VIII

CLASS M -- (Terrestrial)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Surface water abundant; if water or ice covers more than 80% of surface, is considered to be Class O or Calls P
Atmosphere: -- Nitrogen, Oxygen, trace elements
Evolution: -- n/a
Life Forms: -- Extensive vegetation, animal life, humanoids
Example: -- Earth, Vulcan, Cardassia Prime

CLASS N -- (Reducing)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- High surface temperature due to greenhouse effect; water exists only as vapor
Atmosphere: -- Extremely dense; carbon dioxide and sulfides
Evolution: -- n/a
Life Forms: -- Unknown
Example: -- Venus

CLASS O -- (Pelagic)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Liquid water covers over 80% or more of surface area
Atmosphere: -- Nitrogen, Oxygen, Trace elements
Evolution: -- n/a
Life Forms: -- Aquatic vegetation, animal life, humanoids
Example: -- Argo

CLASS P -- (Glaciated)

Diameter: -- 10,000 - 15,000 km
Location: -- Ecosphere
Surface: -- Water ice covers over 80% or more of surface area
Atmosphere: -- Nitrogen, Oxygen, trace elements
Evolution: -- n/a
Life Forms: -- Hardy vegetation, animal life, humanoids
Example: -- Exo III

CLASS P -- (Glaciated)

Diameter: -- 4,000 - 15,000 km
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
Evolution: -- Cools to become Class C
Life Forms: -- n/a
Example: -- Genesis Planet

CLASS S-T -- (Ultragiant)

Diameter: -- 10,000,000 - 50,000,000 km (Class S)
50,000,000 - 120,000,000 km (Class T)
Location: -- Cold Zone
Surface: -- Tenuous, comprised of gaseous hydrogen and hydrogen compounds; radiates considerable heat
Atmosphere: -- Zones vary in temperature, pressure and composition; water vapor may be present
Evolution: -- n/a
Life Forms: -- Unknown
Example: -- n/a

CLASS Y -- (Demon)

Diameter: -- 10,000,000 - 50,000,000 km
Location: -- Hot Zone / Ecosohere / Cold Zone
Surface: -- Temperature can exceed 500 k
Atmosphere: -- Turbulent, saturated with toxic chemicals and thermionic radiatio
Evolution: -- n/a
Life Forms: -- None
Example: -- Mimetic