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.

About Nereid

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.

Physical Properties

Mean radius170 km

Mass3.1e19 kg

Bond albedo0.155

Orbit

OrbitsNeptune

Semi-major axis5,513,400 km

Eccentricity0.7507

Inclination7.09°

Orbital period360.13 d

Gallery

Hand-picked mission imagery of Nereid sourced from NASA and partner archives. Click any photo for full resolution and source attribution.

Neptune's distant moon Nereid, seen as a faint point by Voyager 2. NASA/JPL-Caltech · Public Domain u2014 NASA Media Usage Guidelines

Imagery on this page is provided by the original mission teams. Full attribution terms: Image Rights & Credits.

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: 2026-06-08 01:37:02.