A moon of Neptune, Naiad (nye'-ad [UK, US] or nay'-ad [US]; Greek plural Ναϊάδ-ες) is named after the Naiads of Greek legend.
Naiad was discovered in August, 1989 from the images taken by the Voyager 2 probe. The last moon to be discovered during the flyby, it was designated S/1989 N 6. It is also designated Neptune III.
It is irregularly shaped and shows no sign of any geological modification. Since its orbit is below Neptune's synchronous orbit radius it is slowly decaying due to tidal forces and will one day impact on Neptune's surface, or will break up into a planetary ring due to tidal forces (once inside its Roche limit).
- Orbital radius: 48,227 km
- Radius: 48 x 30 x 26 km
- Mass: 1.9×1017 kg
- Estimated density: 1.2 g/cm3
- Orbital period: 0.294 d (7 h 6 min)
- Orbital inclination: 4.746°