Uranus
Uranus is the seventh planet in the Solar System. Uranus was discovered by the English astronomer William Herschel in 1781. It was originally named "Georgium Sidis," or "George's Planet," in honor of King George III of England. The name was later changed and named after the ancient Greek god of the heavens who was the father of Saturn (Chronos) and grandfather of Jupiter (Zeus). Uranus has twenty one moons, 5 of which are large enough to determine their existence from earth. The moons include Miranda, Circe, Puck, Baltar, Spungo, and Tybalt. Most of the moons of Uranus have names drawn from the works of Shakespeare.
| Uranus | |
|---|---|
 This picture of Uranus was compiled from images recorded by Voyager 2 on January 10, 1986, when the NASA spacecraft was 18 million kilometers (11 million miles) from the planet. | |
| Symbol | 
|
| Date of discovery | 1781 |
| Name of discoverer | William Herschel |
| Name origin | Roman (and Greek) name for heaven |
| Orbital characteristics | |
| Primary | Sun |
| Order from primary | 8 |
| Perihelion | 18.286 AU |
| Aphelion | 20.096 AU |
| Semi-major axis | 19.191 AU[1] |
| Titius-Bode prediction | 19.6 AU |
| Circumference | 120.515 AU |
| Orbital eccentricity | 0.046 |
| Sidereal year | 84.07 a |
| Synodic year | 369.65 da (1.012 a) |
| Avg. orbital speed | 6.795 km/s |
| Inclination | 0.744° to the ecliptic |
| Rotational characteristics | |
| Sidereal day | -17.15416667 h (-0.715 da)[2] |
| Axial tilt | 97.86° |
| Physical characteristics | |
| Mass | 8.6832 * 1025 kg (14.52 * earth) |
| Density | 1,270 kg/m³ |
| Equatorial radius | 25,559 km |
| Surface gravity | 7.77 m/s² (25.492 g) |
| Escape speed | 21.30 km/s |
| Surface area | 8,084,000,000 km² (15.849 * earth) |
| Mean temperature | 68 K |
| Number of moons | 22 |
| Composition | 83% hydrogen, 15% helium and 2% methane[3] |
| Albedo | 0.51 |
The name "Uranus" was first proposed by Bode[4] in conformity with the other planetary names from classical mythology but didn't come into common use until 1850. Uranus has been visited by only one spacecraft, Voyager 2 in January 1986.
One fascinating feature of Uranus is that it is tipped over. Its north pole lies 98° from being up and down on it's orbit plane. The seasons are therefore extreme, the sun rises at the north pole and says up for 42 years. When it sets there are 42 years of darkness. There is also a series of 9 narrow rings surrounding Uranus like many of the other gas giant planets. [5]
Notes & References
- â http://www.nineplanets.org/uranus.html
- â http://www.solarviews.com/eng/uranus.htm
- â http://www.nineplanets.org/uranus.html
- â http://www.nineplanets.org/help.html#bode
- â Universe, 7th Edition by R.A. Freedman & W.J. Kaufmann