Portia is an inner satellite of

Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...

. It was discovered from the images taken by ''

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants (Jupiter and Saturn) and enabled further encounters with the ice giants (Uranus and ...

'' on 3 January 1986, and was given the temporary designation S/1986 U 1. The moon is named after Portia, the heroine of

William Shakespeare William Shakespeare ( 23 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's nation ...

's play ''

The Merchant of Venice ''The Merchant of Venice'' is a play by William Shakespeare, believed to have been written between 1596 and 1598. A merchant in Venice named Antonio defaults on a large loan taken out on behalf of his dear friend, Bassanio, and provided by a ...

''. It is also designated Uranus XII. Portia is the second-largest inner satellite of Uranus after Puck. The Portian orbit, which lies inside Uranus's synchronous orbital radius, is slowly decaying due to

tidal deceleration Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon) and the primary planet that it orbits (e.g. Earth). The acceleration causes a gradual recession of a satellite in a prograde orbit (satel ...

. The moon will one day either break up into a

planetary ring A ring system is a disc or torus orbiting an astronomical object that is composed of solid material such as dust, meteoroids, planetoids, moonlets, or stellar objects. Ring systems are best known as planetary rings, common components of sate ...

or hit Uranus. It is the namesake of a group of satellites called the Portia group, which includes

Bianca Bianca is a feminine given name. It means "white" and is an Italian cognate of Blanche. It is known in the Anglosphere as a character in William Shakespeare's ''The Taming of the Shrew''. It came to greater notice in the 1970s, due to public fi ...

Cressida Cressida (; also Criseida, Cresseid or Criseyde) is a character who appears in many Medieval and Renaissance retellings of the story of the Trojan War. She is a Trojan woman, the daughter of Calchas, a Greek seer. She falls in love with Troilus, ...

Desdemona Desdemona () is a character in William Shakespeare's play ''Othello'' (c. 1601–1604). Shakespeare's Desdemona is a Venice, Italy, Venetian beauty who enrages and disappoints her father, a Venetian senator, when she elopes with Othello (char ...

Juliet Juliet Capulet () is the female protagonist in William Shakespeare's romantic tragedy ''Romeo and Juliet''. A 13-year-old girl, Juliet is the only daughter of the patriarch of the House of Capulet. She falls in love with the male protagonist Ro ...

, Rosalind,

Cupid In classical mythology, Cupid ( , meaning "passionate desire") is the god of desire, erotic love, attraction and affection. He is often portrayed as the son of the love goddess Venus and the god of war Mars. He is also known as Amor (Latin: ...

, Belinda, and Perdita. These satellites have similar orbits and photometric properties. Little is known about Portia beyond its dimensions of about 156 × 126 km, orbit, and geometric

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

of about 0.08. In ''Voyager 2'' imagery, Portia appears as an elongated object whose major axis points towards Uranus. The ratio of axes of the Portia's

prolate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has cir ...

is 0.8 ± 0.1. Its surface is grey in color. Observations with

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

and large terrestrial telescopes found water ice absorption features in the spectrum of Portia. Observations with

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...

have also found evidence for water ice or hydrated minerals on Portia's surface, and have also confirmed that Portia group members Juliet, Belinda, and Cressida have roughly similar spectra to Portia.

Gallery

File:Portia1.jpg, Portia seen on January 23, 1986.

Notes

References

External links

Portia Profile
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NASA's Solar System Exploration

(by Scott S. Sheppard) {{DEFAULTSORT:Portia (Moon) Moons of Uranus 19860103 Moons with a prograde orbit The Merchant of Venice

Gallery

See also

Notes

References

External links