Even the most casual Star Trek fan is familiar with Class M planets. We do, after all, live on one. The most commonly visited class of planet in Star Trek (thanks to production costs no doubt), Class M worlds can generally be compared to Earth. These are planets that lie in a star system’s ecosphere—or habitable zone—are covered with an abundance of water, and have a hot core, molten rock mantle, thin crust, and plate tectonics. Class M planets have a nitrogen-oxygen atmosphere containing other trace elements, and are generally home to a variety of carbon-based life, including vegetation, animal life, and often humanoids.
The best known examples of Class M planets are Earth, Vulcan, Cardassia, Bajor, Betazed, Romulus, and Qo’noS.
The first use of the term “Class M” in terms of production was in “The Cage,” the unaired original pilot for Star Trek (The Original Series). In chronological order, the first use of the term was in the Enterprise episode “Home.” Enterprise also revealed that Class M is short for the Vulcan term “Minshara Class,” as T’Pol explained in the first season episode “Strange New World.”
A Partial List of Class M Planets
Class M planets seen or referred to in TOS
Alfa 177 (“The Enemy Within”)
Alpha Carinae II (“The Ultimate Computer”)
Amerind (“The Paradise Syndrome”)
Beta Niobe I (also knows as Sarpeidon) (“All Our Yesterdays”)
M-113 (“The Man Trap”)
Magna Roma (“Bread and Circuses”)
Pollux IV (“Who Mourns for Adonais?”)
Class M planets seen or referred to in TNG
Alpha Onias III (“Future Imperfect”)
Angel I (“Angel One”)
Ba’ku (Star Trek Insurrection)
Beta Cassius (also known as Haven) (“Haven”)
Brekka (also known as Delos IV) (“Symbiosis”)
Bringloid V (“Up the Long Ladder”)
Veridian III (“Star Trek Generations”)
Class M planets seen or referred to in DS9
Bopak III (“Hippocratic Oath”)
Casperia Prime (“Change of Heart,” “Inquisition”)
Gaia (“Children of Time”)
Class M planets seen or referred to in VOY
Polaric Ion Planet (“Time and Again”)
Taresia (“Favorite Son”)
Tarok (“Initiations”)
Class M planets seen or referred to in ENT
Andoria (“The Aenar”)
Minshara (“Strange New World”)
Class M planets seen or referred to in TAS
Beta Niobe I (also knows as Sarpeidon) (“The Counter-Clock Incident”)
