Class C - Geoinactive
Age: 2-10 billion years
Diameter: 1,000 - 10,000 km
Location: Ecosphere or Cold Zones
Surface: Low surface temperature
Life-Forms: None known
Examples: Pluto, Psi 2000
Class C planets generally reside in a star's habitable or cold zones. Smaller than Earth, they range from 1,000 to 10,000 kilometers in diameter. Due to low solar radiation and minimal internal heat, Class C planets usually have a frozen atmosphere, which is not compatible with life.
The frozen planet Psi 2000, seen in "The Naked Time" (TOS), is a Class C planet. Prior to the disintegration of the planet in 2266, the entire Federation Science team stationed there was found dead due to the effects of a virus.