Class M - Terrestrial
Age: 3-10 billion years
Diameter: 10,000 - 15,000 km
Surface: Surface water abundant; if water or ice covers more than 80% of surface, the planet is considered Class O or P
Atmosphere: Nitrogen, oxygen, trace elements
Life-Forms: Extensive vegetation, animal life, humanoids
Examples: Earth, Vulcan, Qo’noS, Cardassia Prime
Class M planets of this class are found in a star's habitable zone. Typically 10,000 to 15 thousand kilometers in diameter, they have atmospheres that contain oxygen and nitrogen. Most Class M planets have a fairly think tectonically active crust floating on top of a molten rock mantle which surrounds a liquid metal outer core and a solid inner core composed of metal crystals.
These planets differ in color, cloud cover, and general appearance. However, in most cases water and life forms are abundant on these planets. If water or ice covers more than 80% of surface, the planet is considered Class O or P.
Approximately 75% of all colonized worlds by the Federation are Class M, and most oxygen breathing life forms encountered have Class M home worlds. Earth, Vulcan, Qo'noS and Cardassia Prime are a few examples of Class M planets.