Neptune · natural satellite

Nereid

Mean diameter: 340 km
Mean orbital distance: 5,513,900 km from centre
Orbital period: 360.133 Earth days

Compared with our Moon

Nereid · 340 km

Moon · 3,474.8 km

One diameter scale. Circle shapes compare volume-equivalent diameters; irregular moons are not spheres.

Orbit & discovery

Surface gravity: Not available
Discovery: 1949
Discoverer / team: G.P. Kuiper
Provisional designation: —
JPL satellite ID: 802
Orbital eccentricity: 0.751
Inclination: 5.1 degrees

Inclination reference: ecliptic. Mean-element epoch: 2020-01-01.0 TDB · NEP105.

Diameters use volume-equivalent mean radii, including for irregular bodies. Mean orbital elements describe an orbit; they are not live positions. Missing physical measurements remain unavailable.

Physical measurements & uncertainties

Mean radius · km: 170.00 ±25.00 [1]
GM · km³/s²: 0.00000 ±0.00000 [NEP101]
Density · g/cm³: n/a

Missions in the Neptune system · 1 records

1 launches · 0 linked events

These records cover the planetary system. A system mission did not necessarily visit this moon. Dedicated targets are marked separately; programme events include the journey and briefings. Launch outcomes do not establish arrival, landing success or present spacecraft operation.

Dedicated targets only

PLANETARY SYSTEM

Voyager 2

August 20, 1977 · UTC

Lockheed Martin · Titan IIIE

1 records from the complete 9,386‑record production catalogue.

Sources & measurements