National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
Halimede: 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
14 August 2002
Orbit Size Around Neptune (semi-major axis)
Metric: 16,611,000 km
English: 10,321,597 miles
Scientific Notation: 1.6611x107 km
By Comparison: 0.11104
Periapsis (closest)
Metric: 12,215,729 km
Apoapsis (farthest)
Metric: 21,006,271 km
Sidereal Orbit Period (Length of Year)
5.14464 Earth years
1,879.08 Earth days
By Comparison: Retrograde orbit
Orbit Circumference
Metric: 102,518,463.80 km
Average Orbit Velocity
Metric: 2,273.2 km/h
Orbit Eccentricity
Orbit Inclination
By Comparison: Retrograde orbit
Mean Radius
Metric: 31.0 (assuming an albedo of 0.04) km
English: 19.3 miles
Equatorial Circumference
Metric: 194.8 km
Metric: 124,788 km3
Metric: 89,920,105,985,831,600 kg
Metric: 1.5 g/cm3
Surface Area
Metric: 12,076.28 km2
Surface Gravity
Metric: 0.006 m/s2
Escape Velocity
Metric: 71 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:
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writers: Courtney O'Connor and Bill Dunford
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> NASA Advisory Council
> Open Government at NASA
Last Updated: 7 Mar 2011