Nereid
One of the most eccentric moon orbits known, swinging from 1.4 to 9.7 million km out.
Where it is right now
Nereid is in Pisces, 29.3 AU away.
Computed for 2 August 2026, 17:00 UTC, and recomputed at least hourly. This page is cached, so treat the line above as accurate to the hour rather than to the second. The map shows the live position.
Position from a Kepler propagation of the published elements below, accurate to about an arcminute.
Facts
Every line carries the source it came from.
- Mean radius
- 170 kmSource: NASA/JPL Planetary Satellite Physical Parameters
- Orbits
- Neptune, 5,513,900 km out on averageSource: NASA/JPL Planetary Satellite Mean Elements
- Orbital period
- 360.1 daysSource: NASA/JPL Planetary Satellite Mean Elements
- Orbit shape
- eccentricity 0.7510, inclined 5.10 degrees to the eclipticSource: NASA/JPL Planetary Satellite Mean Elements
- Discovered
- 1949 by G.P. KuiperSource: NASA/JPL Planetary Satellite Discovery Circumstances
Physical size
- Mean radius
- 170 km
- Diameter
- 340 km across
Orbit
Elements are relative to Neptune.
- Average distance from Neptune
- 5.51 million km
- Closest and furthest
- 1.37 million km to 9.65 million km
- Eccentricity
- 0.7510, highly elongated
- Inclination to Neptune's reference plane
- 5.10 degrees
- Orbital period
- 360.1 days
- Longitude of ascending node
- 319.50 degrees
- Argument of periapsis
- 296.80 degrees
- Mean anomaly at J2000.0
- 216.70 degrees
Family
Orbits Neptune.
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Catalog id nereid. 3,172 objects on the map, of which 171 are hand-authored with sourced facts.