 Uranus is the seventh planet in order of distance from the Sun and the third one for dimensions.Casually discovered in 1781 by W. Herschel, Uranus is wound by an atmosphere of hydrogen, helium and methane; to this last element is due its characteristic blue coloration. In the highest layers of the atmosphere, in the circumpolar zones, there are wide formations of hoarfrosts, while in the zones toward the equator there are systems of clouds in fast movement around the planet. One of the most important discoveries of the probe Voyager 2, which arrived near Uranus in 1986, was the presence of a magnetic field, of intensity equal to around a third of the terrestrial one. The axis of such magnetic field is inclinated of 55° in comparison to the axis of rotation. And an ulterior peculiarity of Uranus concerns its axis of rotation, that lies almost on the orbital plan: such characteristic, the only one in the whole Solar System, make that the planet turns alternatively toward the Sun its poles. And since the duration of its revolution is about 84 years, every 40 years the polar zones pass from a long "day" to an as much long night. Uranus is the center of a system of fifteen satellites. |
Average distance from the Sun | 2.869.600.000 km |
|---|---|---|
| Longest distance from the Sun | 3.004.000.000 km | |
| Shortest distance from the Sun | 2.735.000.000 km | |
| Period of revolution | 84,01 years | |
| Period of rotation | 17 hours, 6' (retrograde) | |
| Average orbital velocity | 6,8 km/s | |
| Inclination of the axis | 82° 05' | |
| Inclination of the orbit compared to the ecliptic | 0,8° | |
| Eccentricity of the orbit | 0,047 | |
| Equatorial ray | 25.800 km | |
| Deflection | 0,021 | |
| Mass | 8,68 x 10^25 kg | |
| Density | 1,19 kg/dm³ | |
| Albedo | 0,46 |
