Portia (moon)

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Portia
Discovery

Voyager 2 image of the Uranian moons Portia, Cressida, and Ophelia
Discovered by Stephen P. Synnott / Voyager 2
Discovered in January 3, 1986
Orbital characteristics
Mean radius 66,097 km
Eccentricity 0.0001
Orbital period 0.513196 d
Inclination 0.087° (to Uranus' equator)
Is a satellite of Uranus
Physical characteristics
Mean diameter 156 × 126 km[1]
Surface area ~57,000 km² (estimate)
Volume ~1,300,000 km3 (estimate)
Mass ~1.7×1018 kg (estimate)
Mean density ~1.3 g/cm3 (estimate)
Surface gravity ~0.023 m/s2 (estimate)
Escape velocity ~0.058 km/s (estimate)
Rotation period synchronous (assumed)
Axial tilt zero (assumed)
Albedo 0.07 (assumed)
Surface temp.
min mean max
~64 K (estimate)
Atmospheric pressure 0 kPa

Portia (por'-shə, IPA: [ˈpɔrʃə]) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 1986-01-03, and was given the temporary designation S/1986 U 1.[2]

The moon is named after Portia, the heroine of William Shakespeare's play The Merchant of Venice. It is also designated Uranus XII.[3]

Since the Portian orbit lies below Uranus' synchronous orbital radius, it is slowly decaying due to tidal deceleration and will one day either break up into a planetary ring or impact on Uranus' surface.

[edit] References

  1. ^ Karkoschka, Erich (2001). "Comprehensive Photometry of the Rings and 16 Satellites of Uranus with the Hubble Space Telescope". Icarus 151: 51–68. DOI:10.1006/icar.2001.6596. Retrieved on 2006-08-05. 
  2. ^ Smith, B. A. (January 16 1986). IAU Circular No. 4164. Retrieved on 2006-08-06.
  3. ^ Planet and Satellite Names and Discoverers. Gazetteer of Planetary Nomenclature. USGS Astrogeology (July 21 2006). Retrieved on 2006-08-06.
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