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Planetary Typology
Terrestrial planets

HermeanMicroterrestrial-SubterrestrialAnyLarge IronSiNoneTrace
SelenianDwarf-SubterrestrialAnySmall IronSiNoneTrace
AreanSubterrestrial-TerrestrialAnySmall IronSiNoneThin CO2Evolved
EuropanDwarf-SubterrestrialVery ColdSmall IronSiSubsurface H2OTraceModerate tidal flexing
TitanianMicroterrestrial-SubterrestrialVery ColdIce-Rock CHydrocarbonsN2CH3, CH4 clouds
IonianDwarf-SubterrestrialAnySmall IronSiNoneTraceMolten surface from massive tidal flexing
Very HotIronSiNoneMassive CO2H2SO4clouds; Cataclysmic geology; Runaway Greenhouse
Very HotAnyAnyNoneNoneMolten surface from solar proximity
AtlasianMegaterrestrialAnyLarge IronAnyNoneMassiveMolten surface from gravity
HadeanAnyAnyAnyAnyNoneThick CO2Molten surface from bombardment
Very HotLarge IronSiNoneMassive N2, NH3 Runaway Greenhouse
Chthonian XericSuperterrestrial-MegaterrestrialCold to HotLarge IronSiNoneThick or Massive N2, CO2, HeFailed gas giant
Chthonian OceanicSuperterrestrial-MegaterrestrialTemperateLarge IronSiH2ON2, CO2, HeFailed gas giant
Athenian XericSubterrestrial-
Temperate to Very HotLarge IronFeNoneCO, CO2Stripped Mantle
Athenian OceanicSubterrestrial-
TemperateLarge IronFeFe(CO)5CO, CO2Stripped Mantle
Artemisan XericSuperterrestrial-MegaterrestrialTemperate to Very HotLarge IronFeNoneCO, CO2, HeStripped Mantle
Artemisian OceanicSuperterrestrial-MegaterrestrialTemperateLarge IronFeFE(CO)5CO, CO2, HeStripped Mantle
Hephestian XericSubterrestrial-
Cold to Very HotLarge IronCNoneN2, CH4, CO
Hephestian OceanicSubterrestrial-
Very Cold to ColdLarge IronCHydrocarbonsN2, CH4, COTheoretical hydrocarbon-based biochemistry
Apollonian XericSuperterrestrial-
Cold to Very HotLarge IronCNoneN2, He, CH4, CO
Apollonian OceanicSuperterrestrial
Very Cold to ColdLarge IronCHydrocarbonsN2, He, CH4, CO
Styxian XericTemperate to HotSiNoneSO2, SO3, O2
Styxian OceanicTemperate to HotSiH2SO4SO2, SO3, O2
Typhonic XericCold to TemperateSiNoneSO2, N2
Typhonic OceanicCold to TemperateSiSO2SO2, N2
Dionysian XericTemperate to HotSiNoneN2, NO2High UV
Dionysian OceanicTemperate to HotSiHNO3N2, NO2High UV
Persephonean XericColdNoneThin NH3, N2Low UV
Persephonean OceanicColdNH3, H2OThin NH3, N2Low UV
Theoretical ammonia-based biochemistry
Eosian XericSubterrestrial-
Cold to HotLarge IronSiNoneCO2, N2Smaller Eosians must be young
Eosian OceanicSubterrestrial-
TemperateLarge IronSiH2OCO2, N2Water clouds
Eosian PanthalassicSubterrestrial-
TemperateLarge IronSiMassively deep H2OCO2, N2
Archean XericSubterrestrial-
Cold to HotLarge IronSiNoneCO2, N2, O2Carbon-Water biochemistry
Smaller Archeans must be young
Archean OceanicSubterrestrial-
TemperateLarge IronSiH2O CO2, N2, O2
Terran HestianSubterrestrial-
TemperateLarge IronSiH2ON2, O2, CO2Oceanic; Simple Carbon-Water biochemistry
Smaller Terrans must be young
Terran GaeanTerrestrial-
TemperateLarge IronSiH2ON2, O2Oceanic; Complex Carbon-Water biochemistry
Terran TithonianSubterrestrial-
TemperateLarge IronSiH2ON2, O2Carbon-Water biochemistry
Limited tectonics
Oceans dissociating
Terran MelpomeneanTerrestrial-
TemperateLarge IronSiH2ON2, O2, Cl2Oceanic; Carbon-Water-Chlorine biochemistry
Terran CryogenianSubterresrial-
Cold-TemperateLarge IronSiH2ON2, O2Runaway Glaciation
Carbon-Water biochemistry

Oceanic worlds may be arid (mostly land), pontic (mix of oceans and landmasses), epeiric (mostly shallow seas), nesoic (mostly ocean with islands), or pelagic (entirely ocean).

Dwarf planets are large enough to maintain hydrostatic equilibrium but are typically less than one percent Earth mass; microterrestrial are between 1 and 5 percent; subterrestrial between 5 and 50 percent; terrestrial between 50 and 200 percent; superterrestrial between 2 and 5 Earth masses, and megaterrestrial between 5 and 10 Earth masses. Jovian planets range between 10 Earth masses and 4,300 Earth masses. Bodies above 4,300 Earth masses (13.5 Jupiter masses) may fuse deuterium and are considered brown dwarfs.

Gas Giants
Psamathean (Sandy Jovian): Extremely hot with silicate and iron clouds; dark muddy brown to white and green
Salacian (Alkali Jovian): Very hot with sodium and potassium clouds; dark muddy brown to dark gray
Theian (Clarified Jovian): Warm to hot with no clouds; deep blue
Acheronan (Sulfur Jovian): Temperate with sulfurous clouds; yellow and gold
Tethysian (Ice Jovian): Cold to temperate with water clouds; blue and white
Jovian (Ammonia Jovian): Very cold with ammonia clouds; gold, tan, brown, white
Posidean (Methane Jovian): Extremely cold with methane clouds; cyan to blue

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