Nereid
Moon· orbits Neptune
Nereid is a small, distant moon of Neptune on one of the most eccentric orbits of any moon, swinging from ~1.4 to ~9.7 million km.
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Key facts
Radius
170 km
10% of our Moon's radius
Orbit around Neptune
360 Earth days
0.99 Earth years
Science
Physical
- Radius
- 170 km · 10% of our Moon's radius
- JPL / IAU mean radii; spacecraft-tracked GM where measured
Orbit around Neptune
- Distance from Neptune
- 5,513,900 km
- From JPL orbital elements
- Orbital period
- 360.1 days
- From JPL orbital elements
- Eccentricity
- 0.751
- From JPL orbital elements
- Inclination to the ecliptic
- 5.10 °
- From JPL orbital elements
Rotation
- Rotation
- Uncertain and not synchronous — light-curves have suggested a period near ~11 hours, but the measurement remains debated. Not tidally locked.
Composition
- Bulk composition
- A small icy body; its make-up is poorly known but presumed to be water ice and rock.
Radiation & temperature
- Insolation
- 0.00112 S⊕ · 1/892 of the sunlight Earth receives
- Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
- Geometric albedo
- 0.24
- Geometric (V-band) albedo; data limited.
- Equilibrium temperature
- 48 K (-226 °C)
- Computed from albedo + distance from the Sun (airless black body); uses the geometric albedo as an estimate
Discovery & history
- Discovered
- May 1, 1949
- By
- Gerard P. Kuiper
- Method
- Photographic plates
- Name
- The Nereids, the fifty sea-nymph daughters of Nereus in Greek myth.
Kuiper discovered Nereid in 1949. It follows one of the most eccentric orbits of any moon, swinging from roughly 1.4 to 9.6 million km from Neptune, so its distance and brightness change dramatically over its nearly year-long orbit.
Images
Images from open archives · credit shown per image