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Solar System Exploration
Psamathe: Facts & Figures
   Back to Neptune   Overview   Gallery   Facts & Figures 
Discovered By
Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna
Date of Discovery
29 August 2003
Orbit Size Around Neptune (semi-major axis)
Metric: 48,096,000 km
English: 29,885,469 miles
Scientific Notation: 4.8096x107 km
Periapsis (closest)
Metric: 29,776,234 km
Apoapsis (farthest)
Metric: 66,415,766 km
Sidereal Orbit Period (Length of Year)
24.8440794 Earth years
9,074.3 Earth days
By Comparison: Retrograde orbit
Orbit Circumference
Metric: 290,917,287.50 km
Average Orbit Velocity
Metric: 1,335.8 km/h
Orbit Eccentricity
Orbit Inclination
By Comparison: Retrograde orbit
Mean Radius
Metric: 20.0 (assuming an albedo of 0.04) km
English: 12.4 miles
Equatorial Circumference
Metric: 125.7 km
Metric: 33,510 km3
Metric: 14,986,684,330,971,900 kg
Scientific Notation: 1.4987x1016 kg
Metric: 1.5 g/cm3
Surface Area
Metric: 5,026.55 km2
Surface Gravity
Metric: 0.003 m/s2
Escape Velocity
Metric: 36 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