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Nereid: Overview
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Fuzzy black and white image of Nereid.
This fuzzy Voyager 2 image taken in 1989 helped scientists determine Nereid's size.

Nereid is one of the outermost of Neptune's known moons and is among the largest. Nereid is unique because it has one of the most eccentric orbits of any moon in our solar system. Nereid is so far from Neptune that it requires 360 Earth days to make one orbit. This odd orbit suggests that Nereid may be a captured asteroid or Kuiper Belt object or that it was greatly disturbed during the capture of Neptune's largest moon Triton.

Nereid was discovered on 1 May 1949 by Gerard P. Kuiper with a ground-based telescope. It was the last satellite of Neptune to be discovered before Voyager 2's discoveries four decades later.

How Nereid Got its Name:
Moons of Neptune are named for characters from Greek or Roman mythology associated with Neptune or Poseidon, or the oceans. Irregular satellites are named for the Nereids, daughters of Nereus and Doris and the attendants of Neptune.

Nereid (NEER-ee-ed) is named after the Nereids, sea-nymphs, in Greek mythology. Kuiper proposed the name when he reported his discovery.

Just the Facts
Orbit Size (semi-major axis):  5,513,818 km
Mean Radius:  170 km
Volume:  20,579,526 km3
Mass:  30,872,569,721,802,200,000 kg
People Spotlight
Gerard Kuiper Gerard Kuiper
Gerard Kuiper is regarded by many as the father of modern planetary science. His theories led to the discovery of the Kuiper Belt. Read More...
22 Jan 2003: 
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Last Updated: 12 Aug 2013