Bianca (moon)

Voyager 2 Bradford A. Smith

Bianca (also Uranus VIII) is the third and one of the smaller of the 27 known moons of Uranus.

Discovery and designation

Bianca was discovered on 23 January 1986 by the astronomer Bradford A. Smith on photographic images of the Voyager 2 spacecraft. She was the last moon, which was found by the flyby of the probe. The discovery was announced on 27 January 1986 by the International Astronomical Union ( IAU); the moon first received the provisional designation S/1986 U 9

Bianca is the younger sister of Katherina in William Shakespeare's comedy The Taming of the Shrew. Since their father Baptista will agree to a marriage of his younger daughter until the elder daughter Catherine, for those interested, no man is married, has Lucentio, who is in love with Bianca, find a husband for Katherina. With some tricks, he manages to conquer Bianca's heart and win her father's consent.

It was originally planned to name the moon after Peaseblossom, an elf from the Shakespeare comedy A Midsummer Night's Dream, but the name Bianca of the International Astronomical Union a few years by a conflict of nomenclature between the U.S. and the USSR (IAU ) implied by the discovery of the moon selected.

All the moons of Uranus are named after characters from Shakespeare or Alexander Pope. The first four moons discovered Uranus ( Oberon, Titania, Ariel, Umbriel ) were proposed by John Herschel, the son of Uranus discoverer William Herschel, named. Later, the tradition of naming was retained.

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Orbit

Bianca orbiting Uranus on a prograde, nearly perfectly circular orbit at an average distance of about 59,165 kilometers (about 2,315 Uranus radii ) from its center, ie 33,607 km above the cloud tops. The orbital eccentricity of 0.00092, the orbit is inclined 0.19308 ° relative to the equator of Uranus.

Bianca is the innermost moon of the Portia Group, which also includes Cressida, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita belong. These moons have similar orbits and similar spectral properties.

The orbit of the next inner moon Ophelia is on average 5403 kilometers away from Bianca's orbit, the moon of the next outer Cressida 2601 km.

Bianca is located in the midst of two Uranus rings, inside of ongoing ε ( epsilon) - ring which is removed on average about 8017 km from the Bianca- orbit, and the inner edge of the outer ν ( Ny ) dust ring in the 6934 km distance.

Bianca runs around Uranus in 10 hours, 25 minutes and 47.62 seconds. Since this is faster than the rotation of Uranus is Bianca seen from Uranus from the west, and set in the east.

It moves within a critical distance, near the Roche limit, in a descending orbit around the planet and will eventually be torn apart as a result of tidal forces into a ring or plunge into Uranus ' atmosphere or burn up.

Rotation

It is believed that Bianca synchronously rotates and its axis having an inclination of 0 °.

Physical Properties

Bianca has an average diameter of 51.4 km. In the shots of the Voyager 2 probe Bianca appeared as an elongated object with dimensions of 64 × 46 × 46 km, with the longitudinal axis is aligned with Uranus.

Their average density is much lower than the density of the Earth at 1.3 g/cm3 and points out that the moon is composed mainly of water ice. The little Trabant has a very low albedo of 0.08, that is, 8% of the incident sunlight is reflected from the surface. The Moon is thus a very dark celestial bodies. On its surface, the gravitational acceleration is 0.0086 m/s2, corresponding to less than 1 ‰ of the earth. The average surface temperature of Bianca is estimated at -184 to -209 ° C ( 89-64 K). In the spectrum of the surface of Bianca appears gray.

Otherwise, not much is known about this moon since images of the probe came at a great distance and therefore have a low resolution.

Research

Since the flyby of the Voyager 2 spacecraft, the Uranus system of ground-based observations as well as the Hubble Space Telescope has been studied intensively. The orbital parameters of Bianca could be clarified.

Media

  • Photo © Calvin J. Hamilton
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