Nereid (moon)

Nereid ("NEER ee ed") is the outermost of Neptune's known moons and the third largest, with a diameter of 340 km. Its orbit averages 5,513,400 km in radius, but is highly eccentric and varies from 1,353,600 to 9,623,700 kilometers. This is the most highly eccentric orbit of any known planet or satellite in the solar system. This unusual orbit suggests that it may be a captured asteroid or Kuiper belt object, or possibly that it was perturbed during the capture of Neptune's largest moon Triton. Very little else is known of Nereid.

Nereid was discovered in 1949 by Gerard Kuiper. It is named after the Nereids, sea-nymphs of Greek mythology.

• Orbital radius: 5,513,400 km
  • Apogee: 9,623,700 km
  • Perigee: 1,353,600 km
• Diameter: 340 km
• Mass: Unknown
• Orbital period: 360.1362 days
• Orbital inclination: 27.6°
• Rotation period: 11.52 hours