Proteus

Ownership: UCP
Orbital distance from planet: 117,600 km
Diameter: 418 km (436 x 416 x 402)

Proteus is the sixth of Neptune's known moons and the second largest.

Although Proteus is larger than Nereid, it was not discovered earlier because it is very dark and so close to Neptune that it is difficult to see in the glare of the much brighter planet.

Proteus is irregular (non-spherical) in shape. It is probably about as big as an irregular body can be before its gravity pulls it into a more spherical shape.

The heavily cratered surface shows no signs of geologic activity.