Portia (moon)
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| Discovery | |||||||
|---|---|---|---|---|---|---|---|
 Voyager 2 image of the Uranian moons Portia, Cressida, and Ophelia |
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| 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. |
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| 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 forces and will one day either break up into a planetary ring or impact on Uranus' surface.[citation needed]
[edit] References
- ^ 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.
- ^ Smith, B. A. (January 16, 1986). IAU Circular No. 4164. Retrieved on 2006-08-06.
- ^ Planet and Satellite Names and Discoverers. Gazetteer of Planetary Nomenclature. USGS Astrogeology (July 21, 2006). Retrieved on 2006-08-06.
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| Cordelia · Ophelia · Bianca · Cressida · Desdemona · Juliet · Portia · Rosalind · Cupid · Belinda · Perdita · Puck · Mab Miranda · Ariel · Umbriel · Titania · Oberon Francisco · Caliban · Stephano · Trinculo · Sycorax · Margaret · Prospero · Setebos · Ferdinand |
| See also: Rings of Uranus |
