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Solar System Exploration
Neso: Facts & Figures
   Back to Neptune   Overview   Gallery   Facts & Figures 
Discovered By
Matthew J. Holman, John J. Kavelaars, Tommy Grav, Wesley C. Fraser, and Dan Milisavljevic
Date of Discovery
Orbit Size Around Neptune (semi-major axis)
Metric: 49,285,000 km
English: 30,624,279 miles
Scientific Notation: 4.9285x107 km
Periapsis (closest)
Metric: 21,123,551 km
Apoapsis (farthest)
Metric: 77,446,449 km
Sidereal Orbit Period (Length of Year)
26.6686653 Earth years
9,740.73 Earth days
By Comparison: Retrograde orbit
Orbit Circumference
Metric: 282,584,902.19 km
Average Orbit Velocity
Metric: 1,208.8 km/h
Orbit Eccentricity
Orbit Inclination
By Comparison: Retrograde orbit
Mean Radius
Metric: 30.0 (assuming an albedo of 0.04) km
English: 18.6 miles
Equatorial Circumference
Metric: 188.5 km
Metric: 113,097 km3
Metric: 164,853,527,640,691,000 kg
Scientific Notation: 1.6485 x 1017 kg
Metric: 1.5 g/cm3
Surface Area
Metric: 11,309.73 km2
Surface Gravity
Metric: 0.012 m/s2
Escape Velocity
Metric: 97 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: 6 Feb 2014