Bianca (moon)
| Bianca | |
|---|---|
|
|
| The moon Bianca, captured by Voyager 2 | |
| Provisional or systematic name | S / 1986 U 9 |
| Central body | Uranus |
| Properties of the orbit | |
| Major semi-axis | 59,165.550 ± 0.045 km |
| Periapsis | 59,111.118 km |
| Apoapsis | 59,219.982 km |
| eccentricity | 0.00092 ± 0.000118 |
| Orbit inclination | 0.19308 ± 0.054 (equatorial plane) ° |
| Orbital time | 0.434578986 ± 0.000000022 d |
| Mean orbital velocity | 9.9007 km / s |
| Physical Properties | |
| Albedo | 0.08 ± 0.01 |
| Apparent brightness | 22.5 likes |
| Medium diameter | 51.4 ± 4 (64 × 46 × 46) km |
| Dimensions | ≈ 9.2917 · 10 16 kg |
| surface | ~ 8,300 km 2 |
| Medium density | ≈ 1.3 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0.0086 m / s 2 |
| Escape speed | ≈ 22.0 m / s |
| Surface temperature | ≈ −184 to −209 ° C / 64–89 K |
| discovery | |
| Explorer | |
| Date of discovery | January 23, 1986 |
| Remarks | Physical data relatively imprecise. |
Bianca (also Uranus VIII ) is the third innermost and one of the smaller of the 27 known moons of the planet Uranus .
Discovery and naming
Bianca was discovered on January 23, 1986 by the astronomer Bradford A. Smith on photographs taken by the Voyager 2 space probe . It was the last moon found by the probe's flyby. The discovery was announced on January 27, 1986 by the International Astronomical Union (IAU); the moon was initially given the provisional designation S / 1986 U 9 .
Bianca is the younger sister of Catherine in William Shakespeare's comedy The Taming of the Shrew . Since their father Baptista will only agree to marry his younger daughter when the older daughter Katharina, who no man is interested in, is married, Lucentio, who is in love with Bianca, has to find a husband for Katherina. With a few tricks, he succeeds in conquering Bianca's heart and gaining her father's approval.
The original plan was to name the moon after Peaseblossom , an elf from the Shakespeare comedy A Midsummer Night's Dream , but due to a conflict in nomenclature between the US and the USSR , the name Bianca was tacitly adopted by the International Astronomical Union (IAU) a few years later the discovery of the moon.
All the moons of Uranus are named after characters from Shakespeare or Alexander Pope . The first four Uranus moons discovered ( Oberon , Titania , Ariel , Umbriel ) were named after suggestions by John Herschel , the son of the Uranus discoverer Wilhelm Herschel . Later the tradition of naming was retained.
Track properties
Orbit
Bianca orbits Uranus on a prograde , almost perfectly circular orbit at an average distance of around 59,165 km (approx. 2,315 Uranus radii) from its center, i.e. 33,607 km above its cloud ceiling. The orbital eccentricity is 0.00092, the web is 0.19308 ° to the equator of Uranus inclined .
Bianca is the innermost moon of the Portia group , which also includes Cressida , Desdemona , Juliet , Portia , Rosalind , Cupid , Belinda and Perdita . These moons have similar orbits and similar spectral properties.
The orbit of the next inner moon Ophelia is on average 5,403 km from Bianca's orbit, that of the next outer moon Cressida is 2,601 km.
Bianca is located in the middle of two Uranus rings, the inner ε (epsilon) ring , which is on average around 8,017 km from the Bianca orbit, and the inner edge of the outer ν (Ny) dust ring 6,934 km away.
Bianca orbits Uranus in 10 hours, 25 minutes and 47.62 seconds. Since this is faster than the rotation of Uranus, Bianca rises in the west and sets in the east as seen from Uranus.
It moves within a critical distance, near the Roche limit , in a descending orbit around the planet and will at some point be torn apart as a result of tidal forces into a ring or fall or burn up in Uranus' atmosphere.
rotation
It is believed that Bianca rotates synchronously and that her axis has an incline of 0 °.
Physical Properties
Bianca has a mean diameter of 51.4 km. In the recordings of the Voyager-2 - probe Bianca appeared as an elongate object having dimensions of 64 × 46 × 46 km, wherein the longitudinal axis is aligned with Uranus.
Its mean density of 1.3 g / cm 3 is significantly lower than the density of the earth and indicates that the moon is mainly composed of water ice .
The small Trabant has a very low albedo of 0.08, i.e. That is, 8% of the incident sunlight is reflected from the surface. The moon is therefore a very dark celestial body.
The acceleration due to gravity on its surface is 0.0086 m / s 2 , which corresponds to less than 1 ‰ of that on earth.
The mean surface temperature of Bianca is estimated to be between −184 and −209 ° C (89–64 K ).
The surface of Bianca appears gray in the spectrum .
Otherwise, not much is known about this moon, as the probe images were taken at a great distance and therefore have a low resolution.
exploration
Since the Voyager 2 space probe's flyby, the Uranus system has been studied intensively by both Earth-based observations and the Hubble Space Telescope . In doing so, Bianca's orbit parameters could be specified more precisely.
Web links
- IAUC 4168: Satellites and Rings of Uranus Jan 27, 1986 (discovery)
- IAUC 4609: Satellites of Saturn and Uranus June 8, 1988 (numbering and naming)
- Polish moon page: Bianca - description and further links (English)
- Satellite Viewer - orbit simulation of Uranus' moons