Juliet (moon)
| Juliet | |
|---|---|
 |
|
| Voyager 2 shot of Juliet | |
| Provisional or systematic name | S / 1986 U 2 |
| Central body | Uranus |
| Properties of the orbit | |
| Major semi-axis | 64,358.222 ± 0.048 km |
| Periapsis | 64,315.746 km |
| Apoapsis | 64,400.698 km |
| eccentricity | 0.00066 ± 0.000087 |
| Orbit inclination | 0.06546 ± 0.040 (equatorial plane) ° |
| Orbital time | 0.493065490 ± 0.000000012 d |
| Mean orbital velocity | 9.4922 km / s |
| Physical Properties | |
| Albedo | 0.08 ± 0.01 |
| Apparent brightness | 21.12 ± 0.05 mag |
| Medium diameter | 93.6 ± 8 (150 × 74 × 74) km |
| Dimensions | ≈ 5.5750 · 10 17 kg |
| surface | ~ 35,000 km 2 |
| Medium density | ≈ 1.3 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0.0172 m / s 2 |
| Escape speed | ≈ 40.0 m / s |
| Surface temperature | ≈ −184 to −209 ° C / 64–89 K |
| discovery | |
| Explorer | |
| Date of discovery | January 3, 1986 |
| Remarks | Physical data relatively imprecise. |
Juliet (also Uranus XI ) is the sixth innermost and one of the medium-sized of the 27 known moons of the planet Uranus .
Discovery and naming
Juliet was discovered on January 3, 1986 by astronomer Stephen P. Synnott together with Portia on photographs taken by the Voyager 2 spacecraft . 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 2 .
Juliet is the tragic heroine of William Shakespeare's tragedy Romeo and Juliet (Romeo and Juliet) . Romeo and Juliet are the children of the warring families Montague and Capulet in Verona and keep their love a secret because of the regular feuds; they are secretly married by Father Lorenzo. When Romeo is exiled to Mantua because of the fight with Tybalt, in which he perishes, Juliet is hastily married to Paris according to the will of her ignorant parents. To escape this, Julia takes a sleeping potion on the advice of Father Lorenzo, which puts her in a death-like state. Romeo receives the news of the alleged death of his wife and poisons himself on her open coffin. When Julia wakes up at the same moment and sees what has happened, she stabs herself out of desperation.
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
Juliet orbits Uranus on a prograde , almost perfectly circular orbit at an average distance of around 64,358 km (approx. 2,518 Uranus radii) from its center, i.e. 38,799 km above its cloud ceiling. The orbital eccentricity is 0.00066, the web is 0.06546 ° to the equator of Uranus inclined .
Juliet is the fourth innermost moon in the Portia group , which also includes Bianca , Cressida , Desdemona , Portia , Rosalind , Cupid , Belinda, and Perdita . These moons have similar orbits and similar spectral properties.
The orbit of the next inner moon Desdemona is on average 1,700 km away from Juliet's orbit, that of the next outer moon Portia 1,739 km. So Juliet is almost exactly in the middle of the orbits of these two moons.
Juliet is located in the middle of two Uranus rings, the inner ε (epsilon) ring , which is on average around 13.209 km from the Juliet orbit, and the inner edge of the outer ν (Ny) dust ring at a distance of 1,742 km.
Juliet orbits Uranus in 11 hours, 50 minutes and 0.86 seconds. Since this is faster than the rotation of Uranus, Juliet rises in the west and sets in the east as seen from Uranus.
rotation
It is believed that Juliet rotates synchronously and that her axis is inclined at 0 °.
Physical Properties
Juliet has a mean diameter of 93.6 km. In the recordings of the Voyager-2 - probe Juliet appeared as highly elongated object having dimensions of 150 × 74 × 74 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 .
Juliet has a very low albedo of 0.08, i.e. That is, 8% 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 0.0172 m / s 2 , which corresponds to about 1 ‰ of that on earth.
The mean surface temperature of Juliet is estimated to be between −184 and −209 ° C (89–64 K ).
The surface of Juliet 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.
It is possible that Juliet will collide with the inner Desdemona some 1,700 km away within the next 100 million years .
exploration
Since Voyager 2's flyby, the Uranus system has been studied extensively by both Earth-based observations and the Hubble Space Telescope . Juliet's path parameters could be specified more precisely.
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: Juliet description and further links (English)
- Satellite Viewer Orbit simulation of the Uranus moons