Star Trek planet classifications

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In the fictional Star Trek universe, the Planet Classification System is a system developed by the Federation to categorize planets by many factors, such as atmospheric composition, age, surface temperature, size, and presence of life.

The planet classes were initially developed by series creator Gene Roddenberry. Only a few classes have been mentioned in the Star Trek canon, the most commonly visited worlds being Class "M" or Earth-like terrestrial planets for the obvious reason that advanced humanoid life will most likely exist there.

[edit] Classes mentioned in the series

[edit] Class D

Class D objects are planetoids like asteroids and some moons. The planet Regula, the site of the Genesis experiment was a Class D planetoid. ^[1]

[edit] Class H

Class H planets appear in the series as harsh desert worlds. The planet Tau Cygna V visited by the Enterprise-D was designated as a Class H world.^[2]

[edit] Class J and Class T

Class J and Class T planets are designated gas giants. Class J are smaller than Class T which are considered "super", or "ultra" gas giants — possibly even Brown Dwarfs on the verge of becoming stars. Jupiter and Saturn would fall under Class J-sized gas giant planets. The USS Defiant entered the atmosphere of a Class J gas-giant to rescue the crew of a Karemman ship attacked by the Jem-Hadar.^[3] The USS Voyager encountered a Class T Super-Giant in the Delta Quadrant with "radiogenic" rings.^[4]

[edit] Class K

Class K planets are barren worlds with no native life, however through terraforming they can be made into Class M worlds (see below). In the series the planet Mudd was designated in dialog as Class K.^[5]

[edit] Class L

Class L planets are barely habitable worlds with primitive ecosystems. The planet Indri VIII was indicated in dialog as Class L.^[6]

[edit] Class M

Main article: Class M planet

Class M, or "Terrestrial", planets are the most commonly visited planets in the Star Trek series. They are named after the Vulcan term "Minshara" class. They have atmospheres comprised of nitrogen and oxygen but most importantly they have plenty of liquid water necessary for carbon-based life to exist. Life is almost always present often flourishing as extensive plants and animals. Usually a sentient race is also present. Earth is a textbook example of a Class M world. Other worlds in the series such as Vulcan, Cardassia Prime, Risa (initially seen in "Captain's Holiday"), Bajor, Betazed, Romulus, and Qo'noS are mentioned as being Class M planets.

[edit] Class N

Class N planets have a reducing environment and are barren and rocky with extremely high surface temperatures caused by thick atmospheres containing carbon dioxide and corrosive sulfides. In this case, Venus could be considered Class N as it has a reducing (corrosive) atmosphere. The Class N environment was mentioned as the place to use non-oxidizing explosives. ^[7]

[edit] Class Y

Class Y planets are referred to as "Demon" worlds where surface conditions do not fall into any other recognized category. Such worlds are usually hostile and lethal to humanoid life. If life develops on these worlds they usually take on many bizarre forms, like living crystal or rock, liquid or gaseous physical states, non-corporeal or dimensional states or energy-based. In the series, the planet Tholia, the "Silver Blood" planet discovered by the USS Voyager in the Delta Quadrant in the episode "Demon"^[8], and the home world of the incorporeal Medusan species are considered Class Y "Demon" planets.

[edit] Other classes

Other planetary classes exist designated by all the letters of the alphabet A to Z (with the exceptions of U, V, and W which are not used). These other letter designations are considered semi-canon to the series. ^[9]

• Class A, B and C – Typically small, young planets whose class depends on their age and solidity of their cores.
• Class E, F and G – Typically, Earth-sized planets whose class depends on their age and solidity of their cores.
• Class I – Class of gas giant, larger than Class J, and smaller than Class S and T.
• Class O and P – Planets covered almost completely with water (class O), or water-ice (Class P).
• Class Q – Planets with continually changing environments caused by peculiar orbits, an orbit around a variable output star, or some other factor which causes conditions to drastically change overtime.
• Class R – A rogue planetary body which is one that does not orbit a star but drifts freely in space.
• Class S – Class of gas giant smaller than Class T and the next larger size up from Class I.
• Class X and Z – Reserved for other designations of "demon" planets.

[edit] References

Some planet classifications are also explained in larger detail in The Star Trek Encyclopedia, by Mike & Denise Okuda.

[edit] See also

• List of Star Trek planets

[edit] External links

• Planetary classification article at Memory Alpha, a Star Trek wiki
• Planetary classification Star Trek planets classification and images. (Spanish)