Proserpine is a planetary body in the Sol star system, the tenth planet in orbit.
It was unknown to Earth astronomers until the late 20th century due to the limits of telescope observation. (Last Unicorn RPG module: A Cadet's Guide to Sector 001 Earth)
The planet was named after the Roman goddess of springtime and wife of the god of the underworld. The planet was comprised mainly of rock and ice. (Last Unicorn RPG module: Planets of the UFP)
- The planet's name was misspelled as Prosperine in the solar system maps in Planets of the UFP and Starfleet Academy, and as Prosperpine in A Cadet's Guide to Sector 001 Earth.
- After the Last Unicorn RPG modules were published, the tenth planet of the Sol system was named Eris, and Star Trek media published afterwards reflected that.
