Planet Classification
This list comprises all planet classes and all individual planets of each class that were shown or mentioned on screen. Exception: For Class M, there are just a number of examples from a total of probably over a hundred planets.
I am aware that the classification system has been consistently supplemented in the book Star Trek Star Charts by Geoffrey Mandel to include several more letters, but that is non-canon.
List of Canon Planet Classes
| Class | Name and annotations | Episode | Image |
|---|---|---|---|
| Class D | Regula, "a few unremarkable ores... a great rock in space" | "Star Trek: The Wrath of Khan" |  |
| Planet with ring system | VOY: "Emanations" |  |
|
| Hot, arid, rocky planet | VOY: "Gravity" |  |
|
| Weytahn/Paan Mokar, "uninhabitable" | ENT: "Cease Fire" |  |
|
| Class H | Tau Cygna V, considered uninhabitable for humans because of hyperonic radiation | TNG: "The Ensigns of Command" |    |
| Planet with oxygen/argon atmosphere | VOY: "Scorpion, Part II" |  |
|
| Class J | Gas giant | DS9: "Starship Down" |  |
  Two gas giants in the Laap system, one of which was erroneously drawn to share its orbit with a Class-M planet |
LOW: "First First Contact" | |
|
| Class K | Adaptable for humanoid life with pressure domes | TOS: "I, Mudd" |    |
 Theta VIII, "Class-K transjovian planet" |
TNG: "The Royale" |   |
|
| Class L | Indri VIII, "covered by deciduous vegetation, unexplored, with no apparent evidence of civilizations, either present or past" | TNG: "The Chase" |   |
| Briori planet, now New Earth, oxygen/argon atmosphere | VOY: "The 37's" |  |
|
| Cold planet, "barely habitable" | DS9: "The Ascent" |  |
|
| "Barely breathable atmosphere" with excess carbon dioxide | DS9: "The Sound of Her Voice" |  |
|
| Crash site of USS Voyager in alternate timeline | VOY: "Timeless" |  |
|
| Kelis's homeworld | VOY: "Muse" |  |
|
| Planet with atmosphere | ENT: "Bounty" | |
|
 Kaijur XII, inhabited planet with a food shortage |
DIS: "Scavengers" | |
|
| Kokytos, uninhabited ice moon in orbit of Theta Helios |
DIS: "All Is Possible" |  |
|
| Prospect VII, "very barren, harsh climate" |
SNW: "Lift Us Where Suffering Cannot Reach" |  |
|
| Valeo Beta V, ice planet with heavy storms |
SNW: "All Those Who Wander" |  |
|
| Class M Oxygen/nitrogen atmosphere (countless episodes) |
Earth | TNG: "Conspiracy" and many more |   |
| Organia | TOS: "Errand of Mercy" |   |
|
| Sarpeidon | TOS: "All Our Yesterdays" |   |
|
| Edo planet | TNG: "Justice" |   |
|
| Alpha Onias III, "our survey teams have listed it as barren and inhospitable" | TNG: "Future Imperfect" |   |
|
| Lambda Paz, moon of Pentarus III, "barely Class M" | TNG: "Final Mission" |   |
|
| "Planet Hell", "high amino acid and protein readings... EM disturbances all over the atmosphere" | VOY: "Parturition" |  |
|
| Vulcan designation: Minshara Class | ENT: "Strange New World" |  |
|
| Class N |   No planets mentioned or shown, existence can be inferred from three LCARS displays in two TNG-R episodes |
TNG-R: "Night Terrors", "Inheritance" | |
| Class R |  No planets mentioned or shown, existence can be inferred from LCARS display in TNG-R |
TNG-R: "Night Terrors" | |
| Class T | Gas giant with ring system | VOY: "Good Shepherd" |  |
| Class Y Class nickname: Demon Class |
Toxic atmosphere with thermionic radiation, surface temperatures over 500K | VOY: "Demon" |  |
| Ord'Mirit planet, identified as possible new home by "Silver Blood" crew | VOY: "Course: Oblivion" |  |
|
| Ha'Dara, "Toxic atmosphere, sulphuric deserts, no trees, no life at all" | VOY: "Flesh and Blood" |  |
|
| Dilithium planet(oid), origin of the Burn, flooded with all kinds of radiation |
DIS: "Su'Kal" |  |
|
| Class 9 Pre-Federation classification. Out of the four gas giants in the Sol system, none are Class 9. |
Klingon designation: K'Tal Class | ENT: "Sleeping Dogs" |  |
See Also
Planet Mutations - recurring planets whose appearance varies
Planets in TOS and TOS Remastered - Part 1, Part 2, Part 3 - survey of the TOS planet models and how they were remastered
Re-Used Planets in TNG - all the planets that appeared from twice up to eleven times
Re-Used Planets in DS9 - all the planets that appeared from twice up to six times
Credits
Some screen caps from TrekCore. Data taken from the Star Trek Encyclopedia III, the Star Trek Archive, Chakoteya and Memory Alpha. Thanks to Googolplex for a hint about another Class-L planet.
