Naiad (moon)

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Naiad

Naiad or Thalassa as seen by Voyager 2
(smearing has caused excessive elongation)
Discovery
Discovered by Voyager Imaging Team
Discovered in September 1989
Orbital characteristics
Epoch 18 August 1989
Semi-major axis 48 227 ± 1 km
Eccentricity 0.0004 ± 0.0003
Orbital period 0.2943958 ± 0.0000002 d
Inclination 4.75 ± 0.03° (to Neptune equator)

4.75° (to local Laplace plane)

Is a moon of Neptune
Physical characteristics
Dimensions 96×60×52 km
Mass ~1.9×1017 kg
(based on assumed density)
Mean density ~1.2 g/cm3 (estimate)
Rotation period assumed synchronous
Axial tilt ~zero presumably
Albedo (geometric) 0.07[1]
Surface temp. ~51 K mean (estimate)
Atmosphere none

Naiad or Neptune III is the closest moon to Neptune named after the Naiads of Greek legend. It was found sometime before mid-September, 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. Naiad is not a sphere and probably has not been changed by any internal geological processes after its formation. It orbits about 23,500 km above Neptune's cloud tops.

Since the Voyager 2 flyby, the Neptune system has been studied a lot from ground-based observatories and the Hubble Space Telescope as well. In 2002-03, Keck telescope looked at the system using adaptive optics and detected easily the biggest four closer satellites. Thalassa was found with some image processing, but Naiad was not located.

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A simulated view of Naiad orbiting Neptune with the Sun in the distance.
A simulated view of Naiad orbiting Neptune with the Sun in the distance.


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