Cupid (moon)
| Cupid | |
|---|---|
| Provisional or systematic name | S / 2003 U 2 |
| Central body | Uranus |
| Properties of the orbit | |
| Major semi-axis | 74,392 km |
| Periapsis | 74,295 km |
| Apoapsis | 74,489 km |
| eccentricity | 0.0013 |
| Orbit inclination | 0.099 (equatorial plane) ° |
| Orbital time | 0.618 d |
| Mean orbital velocity | 8.7539 km / s |
| Physical Properties | |
| Albedo | 0.07 |
| Apparent brightness | 26.0 likes |
| Medium diameter | 18 km |
| Dimensions | ≈ 1.2 · 10 15 kg |
| surface | ≈ 1,000 km 2 |
| Medium density | ≈ 1.3 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0.0031 m / s 2 |
| Escape speed | ≈ 7.6 m / s |
| Surface temperature | ≈ −184 to −209 ° C / 64–89 K |
| discovery | |
| Explorer | |
| Date of discovery | August 25, 2003 |
| Remarks | Physical data relatively imprecise. |
Cupid (also Uranus XXVII ) is the ninth innermost and one of the smallest of the 27 known moons of the planet Uranus .
Discovery and naming
Cupid was discovered on August 25, 2003 by astronomers Mark R. Showalter and Jack Jonathan Lissauer together with Mab using the Hubble space telescope. It was the second moon in the solar system to be discovered with this telescope. The discovery was announced on September 25, 2003 by the International Astronomical Union (IAU); the moon was initially given the provisional designation S / 2003 U 2 .
Cupid is named after Cupid , a character from William Shakespeare's little-known tragedy Timon of Athens . Cupid or Cupidus is also another name for the love god Amor from Roman mythology (corresponds to the Greek Eros ).
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
Cupid orbits Uranus on a prograde , almost perfectly circular orbit at an average distance of around 74,392 km (approx. 2,911 Uranus radii) from its center, i.e. 48,833 km above its cloud ceiling. The orbital eccentricity is 0.0013, the web is 0.099 ° relative to the equator of Uranus inclined .
Cupid is the seventh innermost and probably smallest of the Portia group , which also includes Bianca , Cressida , Desdemona , Juliet , Portia , Rosalind , Belinda and Perdita . These moons have similar orbits and similar spectral properties.
The orbit of the next inner moon Rosalind is on average 4,465 km away from Cupid's orbit, that of the next outer moon Belinda is only 864 km away. Amazingly, in contrast to the other moons Perdita and Mab , the orbit of Cupid does not seem to be disturbed .
Cupid is located in the middle of two Uranus rings, the inner ν (Ny) dust ring , whose outer edge is on average around 4,492 km from the Cupid orbit, and the inner edge of the outer μ (My) dust ring 11,600 km away.
Cupid orbits Uranus in 14 hours, 49 minutes and 55.20 seconds. Since this is faster than the rotation of Uranus, Cupid rises in the west and sets in the east as seen from Uranus.
rotation
It is believed that Cupid rotates synchronously and that its axis has an inclination of 0 °.
Physical Properties
Cupid has a mean diameter of about 18 km.
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 .
Cupid has a very low geometric albedo of 0.07, i.e. That is, 7% of the incident sunlight is reflected from the surface. It is therefore a very dark celestial body.
The acceleration due to gravity on its surface is 0.0031 m / s 2 , which corresponds to only about 0.03% of the earth's.
The mean surface temperature of Cupid is estimated to be between −184 ° C and −209 ° C (64–89 K ).
exploration
Since the Voyager 2 space probe flew by, in which Cupid could not be found due to its small size and brightness, the Uranus system has been intensively studied by earth-based observations as well as the Hubble space telescope . The orbit parameters of Cupid could be specified more precisely.
Web links
- IAUC 8209: S / 2003 U 1 and S / 2003 U 2 September 25, 2003 (discovery)
- IAUC 8648: Satellites of Uranus December 29, 2005 (numbering and naming)
- Polish moon page: Cupid description and further links (English)
- Satellite Viewer Orbit simulation of the Uranus moons
- Animation of the Cupid train ( MOV ; 272 kB)
Individual evidence
- ↑ a b Uranian Satellite Fact Sheet (English, last updated: September 14, 2016)