Rosalind (moon)
| Rosalind | |
|---|---|
 |
|
| Image of the Uranus moon Rosalind and some Uranus rings | |
| Provisional or systematic name | S / 1986 U 4 |
| Central body | Uranus |
| Properties of the orbit | |
| Major semi-axis | 69,926.795 ± 0.053 km |
| Periapsis | 69,919.103 km |
| Apoapsis | 69,934.487 km |
| eccentricity | 0.00011 ± 0.000103 |
| Orbit inclination | 0.27876 ± 0.045 (equatorial plane) ° |
| Orbital time | 0.558459529 ± 0.000000019 d |
| Mean orbital velocity | 9.1058 km / s |
| Physical Properties | |
| Albedo | 0.07 |
| Apparent brightness | 21.79 ± 0.13 mag |
| Medium diameter | 72.0 ± 12 (72 × 72 × 72) km |
| Dimensions | ≈ 2.5477 10 17 kg |
| surface | ≈ 16,000 km 2 |
| Medium density | ≈ 1.3 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0.0131 m / s 2 |
| Escape speed | ≈ 31.0 m / s |
| Surface temperature | ≈ −184 to −209 ° C / 64–89 K |
| discovery | |
| Explorer | |
| Date of discovery | January 13, 1986 |
| Remarks | Physical data relatively imprecise. |
Rosalind (also Uranus XIII ) is the eighth innermost and one of the smaller of the 27 known moons of the planet Uranus .
Discovery and naming
Rosalind was discovered on January 13, 1986 by the astronomer Stephen P. Synnott together with Desdemona and Belinda on photographs taken by the Voyager 2 space probe . The discovery was announced on January 16, 1986 by the International Astronomical Union (IAU); the moon was initially given the provisional designation S / 1986 U 4 .
Rosalind is the daughter of the Duke Senior from William Shakespeare's comedy As You Like It . Duke Senior is ousted by his younger brother Friedrich and goes into exile in the Ardennes Forest . When Orlando, who is in love with Rosalind, finds out after a won fight - which was arranged by his older brother Oliver - that Duke Friedrich is disapproving of him, he follows Senior to the Ardennes. Rosalind is then banished by Friedrich and flees disguised as the man "Ganymede" and accompanied by her friend Celia, Friedrich's daughter, also to the Ardennes. She meets Orlando, who believes Rosalind is lost and writes love poems, but does not reveal himself to ask Orlandos about his true feelings for her; she explains that if Orlando woos Ganymede as if it were Rosalind, he would cure his lovesickness, which he agrees with. After Oliver, who had been sent by Friedrich, was saved by Orlando and Oliver fell in love with Celia, she revealed her true identity to Orlando at their wedding.
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
Rosalind orbits Uranus on a prograde , almost perfectly circular orbit at an average distance of around 69,927 km (approx. 2,736 Uranus radii) from its center, i.e. 44,368 km above its cloud ceiling. The orbital eccentricity is 0.00011, the web is 0.27876 ° to the equator of Uranus inclined .
Rosalind is the sixth innermost of the Portia group , which also includes Bianca , Cressida , Desdemona , Juliet , Portia , Cupid , Belinda and Perdita . These moons have similar orbits and similar spectral properties.
The orbit of the next inner moon Portia is on average 3,830 km away from Rosalind's orbit, that of the next outer moon Cupid 4,465 km. Rosalind is close to an 8: 7 orbit resonance with Perdita .
Rosalind is located in the middle of two Uranus rings, its orbit lies almost exactly on the outer edge of the inner ν (Ny) dust ring , while the mean distance to the inner edge of the outer μ (My) dust ring is about 16,000 km.
Rosalind orbits Uranus in 13 hours, 24 minutes and 10.90 seconds. Since this is faster than the rotation of Uranus, Rosalind rises in the west and sets in the east as seen from Uranus. From the point of view of a fictitious observer on Uranus, Rosalind needs almost 3.5 Uranus days for a full apparent orbit and after two orbits (with 6.99 Uranus days, a "Uranus week") is almost at the same place in the Uranus sky, for example 1 ° further west.
rotation
It is believed that Rosalind rotates synchronously and that its axis has an incline of 0 °.
Physical Properties
Rosalind has an average diameter of 72 km. It can be assumed that Rosalind does not have a spherical shape; however, this could not be determined on the images of the Voyager-2 probe.
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 .
It has a very low albedo of 0.07; That is, 7% of the incident sunlight is reflected from the surface. It is therefore a very dark celestial body.
On its surface, the acceleration due to gravity is 0.0131 m / s 2 , which corresponds to about 1 ‰ of that on earth.
The mean surface temperature of Rosalind is estimated to be between −184 and −209 ° C (89–64 K ).
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, Rosalind was able to specify the path parameters.
Web links
- IAUC 4164: Satellites of Uranus January 16, 1986 (discovery)
- IAUC 4165: Satellites of Uranus January 17, 1986 (Correction to IAUC 4164)
- IAUC 4609: Satellites of Saturn and Uranus June 8, 1988 (numbering and naming)
- Polish moon page: Rosalind description and further links (English)
- Satellite Viewer Orbit simulation of the Uranus moons