Planetary Classification: Difference between revisions

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==Classifications==
==Classifications==
===Class A===
===Class A===
* Geothermal rocky body
* Young world not yet solidified
* Insufficiently large to maintain atmosphere, heat following solidification
* Primarily hydrogen-based atmosphere
* Eventually cools to class C


===Class B===
===Class B===
* Geomorteus rocky body
* Orbits close to primary
* Surface temperature high; portions of surface potentially molten
* Little to no atmosphere due to heat and solar ablation


===Class C===
===Class C===
* Geoinactive rocky body
* Transition from Class A
* Geological processes largely halted
* Atmosphere cooled, potentially frozen


===Class D===
===Class D===


* Terrestrial
* Airless body, often an asteroid or moon
* Airless body, often an asteroid or moon


===Class E===
===Class E===
* Geoplastic rocky body
* Young world not yet solidified
* Essentially a large class A
* Transitions to class F


===Class F===
===Class F===
* Geometallic rocky body
* Transition from class E
* Surface partially solidified, geological and geothermal activity still high
* Largely uninhabitable by humanoid life
* Transitions to class G


===Class G===
===Class G===
* Geocrystalline rocky body
* Transition from class F
* Surface essentially solidified
* Temperatures cooling, potentially survivable range
* Thick atmosphere
** Often low oxygen content due to oxygen binding in crust
* Potentially habitable with technological aid
* Transition to class H, K-P


===Class H===
===Class H===


* Terrestrial
* Rocky body
* Arid world
* Very arid world
** High surface temperature
* Little to no surface water
* Atmosphere often saturated with heavy gasses or metallic vapors
* Atmosphere often saturated with heavy gasses or metallic vapors
* Little to no surface water
* Generally uninhabitable to humanoid life
* Generally uninhabitable to humanoid life


===Class I===
===Class I===
* Ice giant
* Atmospheric envelope dominated by ammonia, water, methane
** Hydrogen levels very low (20% or lower) as compared to class J planets


===Class J===
===Class J===
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*** Type 2: 150K-250K, dominated by water vapor clouds
*** Type 2: 150K-250K, dominated by water vapor clouds
*** Type 3: 250K-800K, cloudless
*** Type 3: 250K-800K, cloudless
* Known as [[Fesoan]]-class by [[Andorian Empire|Andorian]]s (ENT Novel: ''Live by the Code'')


===Class K===
===Class K===


* Terrestrial
* Adaptable
* Adaptable world
* Generally thin atmopshere
* Generally thin atmopshere
* Little to no surface water
* Little to no surface water
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===Class L===
===Class L===


* Terrestrial
* Marginal
* Transitioned from class G
* Barely habitable or habitable with minimal technological aid
* Barely habitable or habitable with minimal technological aid
** Often pre-terraforming state
** Often pre-terraforming state
* Native life often limited to flora
** Possibly in process of transitioning to class M


===Class M===
===Class M===


* Terrestrial
* Terrestrial
* Previously known as [[Vulcan (planet)|Minshara]]-class by [[Vulcan Science Directorate]], [[Earth]]-type by [[UESPA]] (ENT, TOS)
* Previously known as [[Vulcan (planet)|Minshara]]-class by Vulcan Science Directorate, Earth-type by [[UESPA]] (ENT, TOS)
* Significant surface water, below 80% coverage
* Significant surface water, below 80% coverage
* Atmosphere consisting of nitrogen, oxygen, trace elements
* Atmosphere consisting of nitrogen, oxygen, trace elements
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===Class N===
===Class N===


* Terrestrial
* Reducing
* Thick atmosphere, often saturated with sulfur compounds
* Thick atmosphere, often saturated with sulfur compounds
* High surface temperature due to atmospheric greenhouse effect
* High surface temperature due to atmospheric greenhouse effect
Line 74: Line 110:


===Class O===
===Class O===
* Pelagic
* Largely identical in composition and habitability to class M
* Liquid water covers 80+% of surface
* Life generally only present if sufficient landmasses to allow for mineral circulation
* Common alternative to class M planets in systems with gravitational disruption of protoplanetary disk leading to increased cometary bombardment (TNG Novel: ''The Buried Age'')
** Examples include distant stellar companions, multiple inward-migrating Jovians  (TNG Novel: ''The Buried Age'')


===Class P===
===Class P===
* Glaciated
* Largely identical in composition to class M
* Surface temperatures below freezing
* Generally covered in water ice
* Often transitioning from prior class due to changes in available surface heat
* Scientific study often based from subglacial bases constructed on rocky core beneath planetary ocean/slush mantle, ice crust (TNG Novel: ''The Buried Age'')


===Class Q===
===Class Q===
* Variable
* Previously known as Quaris-class by Vulcan Science Directorate
* Unpredictable surface and environmental conditions
** Generally wide variations from region to region
* Often caused by variable star output, highly eccentric orbit


===Class R===
===Class R===
* Rogue
* Generally uninhabitable
** Geothermal heat can sometimes maintain ecosystem on surface


===Class S===
===Class S===


* Gas dwarf
* Generally protoplanetary stage progressing towards class I


===Class T===
===Class T===


* Hot gas giant
** Divided into [https://en.wikipedia.org/wiki/Sudarsky%27s_gas_giant_classification two subtypes] by temperature, predominant cloud formation
*** Type 4: 900K-1400K, dominated by alkali clouds
*** Type 5: 1400+K, dominated by silicate clouds
===Class X===
* Miscellaneous classification
* Any planetary status not falling under standard natural planetary development
* ''Unsubstantiated''


===Class Y===
===Class Y===
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** ''Class I ice giant''
** ''Class I ice giant''
** ''Class J cold gas giant''
** ''Class J cold gas giant''
*** ''Type I through V using [https://en.wikipedia.org/wiki/Sudarsky%27s_gas_giant_classification Sudarsky's schema]''
*** ''Type 1 through 3 using [https://en.wikipedia.org/wiki/Sudarsky%27s_gas_giant_classification Sudarsky's schema]''
** ''Class S gas dwarf''
** ''Class S gas dwarf''
*** ''[http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1989A&A...215..177S&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES Theoretical protoplanet state] leading to ice giants, potentially also gas giant that has lost atmosphere to solar wind ablation''
*** ''[http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1989A&A...215..177S&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES Theoretical protoplanet state] leading to ice giants, potentially also gas giant that has lost atmosphere to solar wind ablation''
** ''Class T hot gas giant (fka hot Jupiter)''
** ''Class T hot gas giant (fka hot Jupiter)''
*** ''Type I through V using Sudarsky's schema''
*** ''Type 4 through 5 using Sudarsky's schema''


(''Star Charts'' unless otherwise referenced)
(''Star Charts'' unless otherwise referenced)


[[Category:Astronomy]]
[[Category:Astronomy]]

Latest revision as of 07:42, 26 April 2018

Facts

  • Planetary classification system established by mid-23rd century
  • Descends from similar classification systems established by Vulcan Science Directorate, UESPA (ENT, TOS)

Classifications

Class A

  • Geothermal rocky body
  • Young world not yet solidified
  • Insufficiently large to maintain atmosphere, heat following solidification
  • Primarily hydrogen-based atmosphere
  • Eventually cools to class C

Class B

  • Geomorteus rocky body
  • Orbits close to primary
  • Surface temperature high; portions of surface potentially molten
  • Little to no atmosphere due to heat and solar ablation

Class C

  • Geoinactive rocky body
  • Transition from Class A
  • Geological processes largely halted
  • Atmosphere cooled, potentially frozen

Class D

  • Airless body, often an asteroid or moon

Class E

  • Geoplastic rocky body
  • Young world not yet solidified
  • Essentially a large class A
  • Transitions to class F

Class F

  • Geometallic rocky body
  • Transition from class E
  • Surface partially solidified, geological and geothermal activity still high
  • Largely uninhabitable by humanoid life
  • Transitions to class G

Class G

  • Geocrystalline rocky body
  • Transition from class F
  • Surface essentially solidified
  • Temperatures cooling, potentially survivable range
  • Thick atmosphere
    • Often low oxygen content due to oxygen binding in crust
  • Potentially habitable with technological aid
  • Transition to class H, K-P

Class H

  • Rocky body
  • Very arid world
    • High surface temperature
  • Little to no surface water
  • Atmosphere often saturated with heavy gasses or metallic vapors
  • Generally uninhabitable to humanoid life

Class I

  • Ice giant
  • Atmospheric envelope dominated by ammonia, water, methane
    • Hydrogen levels very low (20% or lower) as compared to class J planets

Class J

  • Cold gas giant
    • Divided into three subtypes by temperature, predominant cloud formation
      • Type 1: 150K or lower, dominated by ammonia clouds
      • Type 2: 150K-250K, dominated by water vapor clouds
      • Type 3: 250K-800K, cloudless
  • Known as Fesoan-class by Andorians (ENT Novel: Live by the Code)

Class K

  • Adaptable
  • Generally thin atmopshere
  • Little to no surface water
  • Surface conditions suitable for life with aid of pressure domes or life support technology (TOS: "I, Mudd")
    • Often pre-terraforming state

Class L

  • Marginal
  • Transitioned from class G
  • Barely habitable or habitable with minimal technological aid
    • Often pre-terraforming state
  • Native life often limited to flora
    • Possibly in process of transitioning to class M

Class M

  • Terrestrial
  • Previously known as Minshara-class by Vulcan Science Directorate, Earth-type by UESPA (ENT, TOS)
  • Significant surface water, below 80% coverage
  • Atmosphere consisting of nitrogen, oxygen, trace elements
  • Habitable by humanoid life
  • Subdivided into type 1-4, indicating most to least suitable for humanoid life (TNG: "The Bonding")

Class N

  • Reducing
  • Thick atmosphere, often saturated with sulfur compounds
  • High surface temperature due to atmospheric greenhouse effect
  • Generally uninhabitable for humanoid life

Class O

  • Pelagic
  • Largely identical in composition and habitability to class M
  • Liquid water covers 80+% of surface
  • Life generally only present if sufficient landmasses to allow for mineral circulation
  • Common alternative to class M planets in systems with gravitational disruption of protoplanetary disk leading to increased cometary bombardment (TNG Novel: The Buried Age)
    • Examples include distant stellar companions, multiple inward-migrating Jovians (TNG Novel: The Buried Age)

Class P

  • Glaciated
  • Largely identical in composition to class M
  • Surface temperatures below freezing
  • Generally covered in water ice
  • Often transitioning from prior class due to changes in available surface heat
  • Scientific study often based from subglacial bases constructed on rocky core beneath planetary ocean/slush mantle, ice crust (TNG Novel: The Buried Age)

Class Q

  • Variable
  • Previously known as Quaris-class by Vulcan Science Directorate
  • Unpredictable surface and environmental conditions
    • Generally wide variations from region to region
  • Often caused by variable star output, highly eccentric orbit

Class R

  • Rogue
  • Generally uninhabitable
    • Geothermal heat can sometimes maintain ecosystem on surface

Class S

  • Gas dwarf
  • Generally protoplanetary stage progressing towards class I

Class T

  • Hot gas giant
    • Divided into two subtypes by temperature, predominant cloud formation
      • Type 4: 900K-1400K, dominated by alkali clouds
      • Type 5: 1400+K, dominated by silicate clouds

Class X

  • Miscellaneous classification
  • Any planetary status not falling under standard natural planetary development
  • Unsubstantiated

Class Y

  • Terrestrial
  • Colloquially known as "demon"-class (VOY: "Demon")
  • Extremely high surface temperatures
  • Corrosive and/or toxic atmosphere
  • Thermionic discharges from surface-level metallic hydrogen deposits common (VOY: "Demon")
  • Planetary conditions can lead to vessel hazards even at standard orbital altitude (VOY: "Demon")

Notes

  • Star Charts classifications flawed w.r.t. giant planets
    • Radii are physically impossible
      • Jupiter diameter ~140,000km, maximum theoretical possible planetary diameter ~400,000km, but class T planets go up to 120m km?
      • Adding more mass generally tends to increase density, not radius; proximity to sun increases size but only so far
    • No acknowledgement of ice giants (not widespread distinction yet at time of writing) despite physically distinct characteristics
      • All Star charts giant classes are predominantly hydrogen-based, ice giants (i.e. Neptune, Uranus) are water/ammonia-based with very slim hydrogen envelopes
    • All gas giants listed as being in "cold zone" beyond ecosphere, which doesn't fit later discoveries
      • Written before discovery of numerous hot Jupiters by various exoplanet surveys
  • Alteration:
    • Class I ice giant
    • Class J cold gas giant
    • Class S gas dwarf
    • Class T hot gas giant (fka hot Jupiter)
      • Type 4 through 5 using Sudarsky's schema

(Star Charts unless otherwise referenced)

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