Portia is the second-largest inner satellite of Uranus after Puck. Portia is the 8th largest Moon of Uranus and the 42th largest moon in the Solar System currently known.
Discovery
Portia was discovered by Stephen P. Synnott, who is an American astronomer and Voyager scientist, from the images taken by Voyager 2 on 3 January 1986.
Naming
The moon was given the temporary designation S/1986 U1.
Portia the moon is named after Portia, the heroine of William Shakespeare's play The Merchant of Venice.
Portia is the heroine of William Shakespeare's The Merchant of Venice. A rich, beautiful, and intelligent heiress, she is bound by the lottery set forth in her father's will, which gives potential suitors the chance to choose between three caskets composed of gold, silver and lead. If they choose the right casket – the casket containing Portia's portrait – they win Portia's hand in marriage. If they choose the wrong casket, they must leave and never seek another woman in marriage.
Stats
Diameter (mean): 135 km
Semi-major axis: 66,097 km
Orbital Period: 0.51 days
Orbit
Portia takes as long to rotate on its axis as it does to make one orbit of Uranus; and therefore always keeps the same hemisphere pointed to Uranus.
The Portian orbit, which lies inside Uranus' synchronous orbital radius, is slowly decaying due to tidal deceleration. The moon will one day either break up into a planetary ring or hit Uranus.
Portia heads a group of satellites called the Portia Group, which includes Bianca, Cressida, Desdemona, Juliet, Rosalind, Cupid, Belinda and Perdita. These satellites have similar orbits and photometric properties.
Physical characteristics
Little is known about Portia beyond its size of about 135 km, orbit and geometric albedo of about 0.08.
In the Voyager 2 images, Portia appears as an elongated object whose major axis points towards Uranus. Portia's surface is grey in color. Observations with Hubble Space Telescope and large terrestrial telescopes found water ice absorption features in the spectrum of Portia.
Exploration Status
No close-up image of Portia has been photographed.
No mission is planned in the foreseeable future.
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