Moon of Neptune Diameter: 416 km Distance: 117640 km (mean) Period: 1.121 days Eccentricity: 0 Inclination: 0.04° Magnitude: 20.3
Proteus was discovered in 1989 by the Voyager 2 spacecraft. Proteus is the second largest of Neptune's known moon. It has an odd box-like shape and if it had just a little more mass it would be able to transform into a sphere. Proteus is heavily cratered, showing no sign of any geological activity.