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Nereid

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MOON

Nereid

A small outer moon of Neptune with one of the most eccentric orbits of any known moon.

Orbits Neptune
  • Most eccentric orbit of any known moon (e u2248 0.75).
  • Ranges from 1.4 million km to 9.7 million km from Neptune.
  • Likely a captured or scattered body from Triton's capture event.

Physical Properties

170 km
3.1e19 kg
0.155

Orbit

Neptune
5,513,400 km
0.7507
7.09°
360.13 d

Sources & Further Reading

Numerical values (radius, mass, orbital elements, temperatures) are drawn from NASA NSSDC Planetary Fact Sheets, JPL Horizons, and the JPL Small-Body Database. Last refreshed: 2026-04-18 18:19:25.

Nereid is Neptune’s third-largest moon and one of the most eccentric satellite orbits known — ranging between ~1.4 and ~9.7 million km from the planet. Like Triton, it is believed to have been scattered into this wild orbit during Triton’s capture.