Pluto

Class:   Dwarf Planet (orbiting Sol)
Discovered:  1930

Facts:

Greek god of the underworld. The name was suggested by Venetia Burney (19182009), an 11YO schoolgirl from Oxford, England.

Details:

Magnitude:  13.6500 (app) (abs)
Rotation period:  -6 days 9 hrs 17 mins
Atmosphere:  nitrogen, methane, carbon monoxide
Adjective:  Plutonian