Nereid (moon)
Nereid imaged by Voyager 2 in 1989 | |
| Discovery | |
|---|---|
| Discovered by | Gerard P. Kuiper |
| Discovery date | 1 May 1949 |
| Designations | |
Designation | Neptune II |
| Pronunciation | /ˈnɪəriəd/ NEER-ee-əd |
Named after | Νηρηΐδες Nērēḯdes |
| Adjectives | Nereidian or Nereidean (both /ˌnɛriˈɪdiən/ NERR-ee-ID-ee-ən) |
| Orbital characteristics | |
| Epoch 1 January 2020 (JD 2458849.5) | |
| Observation arc | 27,808 d (76.13 yr) |
| 5,504,000 km (0.03679 AU) | |
| Eccentricity | 0.749 |
| 360.14 d (0.9860 yr) | |
| 318.0° | |
| 0° 59m 58.597s / day | |
| Inclination | 5.8° (to the ecliptic) 7.090° (to local Laplace plane) |
| 326.0° | |
| 290.3° | |
| Satellite of | Neptune |
| Physical characteristics | |
| 357±13 km | |
| Flattening | ≤0.23 |
| Mass | 3.57×1019 kg (5.98×10−6 M🜨) |
Mean density | 1.5 g/cm3 (assumed) |
| ≈0.075 m/s2 (0.0076 g) | |
| 11.594±0.017 h | |
| Albedo | 0.24 |
| Temperature | ≈50 K (mean estimate) |
| 19.2 | |
| 4.4 | |
Nereid, or Neptune II, is the third-largest moon of Neptune. It has the most eccentric orbit of all known moons in the Solar System. It was the second moon of Neptune to be discovered, by Gerard Kuiper in 1949.