Planet Neptune

Some Facts about The Neptunian Moon, Proteus
courtesy of NASA

Discovered ByS. Synnott, Voyager 2
Date of Discovery1989
Average Distance from Neptune117,650 km km (metric)
Equatorial Radius218 x 208 x 201 km (metric)
Mass800,000,000,000,000,000 kg (metric)
Orbit Period (Length of Year)1.122315 Earth days
Orbital Eccentricity0.0004
Orbital Inclination to Ecliptic0.55°
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