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Solar System Exploration
Sao: Facts & Figures
   Back to Neptune   Overview   Gallery   Facts & Figures 
Discovered By
Tommy Grav, Matthew J. Holman, John J. Kavelaars, Wesley C. Fraser, and Dan Milisavljevic
Date of Discovery
14 August 2002
Orbit Size Around Neptune (semi-major axis)
Metric: 22,228,000 km
English: 13,811,839 miles
Scientific Notation: 2.2228x107 km
Periapsis (closest)
Metric: 19,193,878 km
Apoapsis (farthest)
Metric: 25,262,122 km
Sidereal Orbit Period (Length of Year)
7.974592745 Earth years
2,912.72 Earth days
Orbit Circumference
Metric: 139,009,795.11 km
Average Orbit Velocity
Metric: 1,988.5 km/h
Orbit Eccentricity
Orbit Inclination
Mean Radius
Metric: 22.0 (assuming an albedo of 0.04) km
English: 14.0 miles
Equatorial Circumference
Metric: 138.2 km
Metric: 44,602 km3
Metric: 89,920,105,985,831,600 kg
Scientific Notation: 8.9920x1016 kg
Metric: 1.5 g/cm3
Surface Area
Metric: 6,082.12 km2
Surface Gravity
Metric: 0.012 m/s2
Escape Velocity
Metric: 84 km/h

Additional Information:

-USGS Astrogeology: Gazetteer of Planetary Nomenclature:

-JPL Solar System Dynamics:

-Solar System Moons: Discovery and Mythology by Jürgen Blunck; Springer-Verlag Berlin Heidelberg 2010

-Encyclopedia of the Solar System, second edition; edited by Lucy-Ann McFadden, Paul R. Weissman, and Torrence V. Johnson; Academic Press 2007

-Ellis Miner

-Encyclopædia Britannica Online. 2010:
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Last Updated: 7 Mar 2011