Despina (moon)

Despina
Despina as seen by Voyager 2 (smeared horizontally)
Discovery
Discovered byStephen P. Synnott and Voyager Imaging Team
Discovery dateJuly 1989
Designations
Designation
Neptune V
Pronunciation/dəˈspaɪnə, dəˈspiːnə, dɛ-/
Named after
Δέσποινα Despœna
AdjectivesDespinian
Orbital characteristics
Epoch 18 August 1989
52 525.95 km
Eccentricity0.00038 ± 0.00016
0.33465551 ± 0.00000001 d
Inclination
  • 0.216 ± 0.014° (to Neptune equator)
  • 0.06° (to local Laplace plane)
Satellite ofNeptune
Physical characteristics
Dimensions(180±6) × (148±12) × (128±6) km
Mean radius
75±3 km
Volume~1.8×106 km3
Mass~(0.71–1.4)×1018 kg
Mean density
0.4–0.8 g/cm3
~0.006–0.023 m/s2
~0.032–0.054 km/s
synchronous
zero
Albedo0.09
Temperature~51 K mean (estimate)
22.0

Despina /dɛˈspaɪnə/, also known as Neptune V, is the third-closest inner moon of Neptune. It is named after Greek mythological character Despoina, a nymph who was a daughter of Poseidon and Demeter.

Discovery

Despina was discovered in late July 1989 from the images taken by the Voyager 2 probe. It was given the temporary designation S/1989 N 3. The discovery was announced (IAUC 4824) on 2 August 1989, and mentions "10 frames taken over 5 days", implying a discovery date of sometime before July 28. The name was given on 16 September 1991.

Physical characteristics

Despina's diameter is approximately 150 kilometres (93 mi). Despina is irregularly shaped and shows no sign of any geological modification. It is likely that it is a rubble pile re-accreted from fragments of Neptune's original satellites, which were disrupted by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit.

Orbit

Despina's orbit lies close to but outside of the orbit of Thalassa and just inside the Le Verrier ring and acts as its shepherd moon. As it is also below Neptune's synchronous orbit radius, it is slowly spiralling inward due to tidal deceleration and may eventually impact Neptune's atmosphere, or break up into a planetary ring upon passing its Roche limit due to tidal stretching.

A simulated view of Despina orbiting Neptune

This page was last updated at 2024-03-28 15:23 UTC. Update now. View original page.

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