Properties

    Uranus is the seventh planet from the Sun and is the third largest in the solar system.

    It was discovered by William Herschel in 1781.

    It has an equatorial diameter of 51,800 kilometers (32,190 miles) and orbits the Sun once every 84.01 Earth years.

    It has a mean distance from the Sun of 2.87 billion kilometers (1.78 billion miles). The length of a day on Uranus is 17 hours 14 minutes.

    Uranus has at least 15 moons. The two largest moons, Titania and Oberon, were discovered by William Herschel in 1787.

Atmosphere

    The atmosphere of Uranus is composed of 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and other hydrocarbons.

    Methane in the upper atmosphere absorbs red light, giving Uranus its blue-green color.
 
Peculiar properties

    Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the solar system's history.

    The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet.

Uranus Statistics

Discovered by --------------------------------------------------------------- William Herschel
Date of discovery ------------------------------------------------------------ 1781
Mass (kg) -------------------------------------------------------------------- 8.686 x 10²⁵
Mass (Earth = 1) ------------------------------------------------------------- 14.535
Equatorial radius (km) -------------------------------------------------------- 25,559
Equatorial radius (Earth = 1) -------------------------------------------------- 4.0074
Mean density (gm/cm³) ------------------------------------------------------- 1.29
Mean distance from the Sun (km) --------------------------------------------- 2,870,990,000
Mean distance from the Sun (Earth = 1) --------------------------------------- 19.1914
Rotational period (hours) ------------------------------------------------------ -17.9
Orbital period (years) ---------------------------------------------------------- 84.01
Mean orbital velocity (km/sec) ------------------------------------------------- 6.81
Orbital eccentricity ------------------------------------------------------------- 0.0461
Tilt of axis (degrees) ----------------------------------------------------------- 97.86
Orbital inclination (degrees) ---------------------------------------------------- 0.774
Equatorial surface gravity (m/sec²) --------------------------------------------- 7.77
Equatorial escape velocity (km/sec) -------------------------------------------- 21.30
Visual geometric albedo -------------------------------------------------------- 0.51
Magnitude (Vo) ---------------------------------------------------------------- 5.52
Mean cloud temperature -------------------------------------------------------- -193°C
Atmospheric pressure (bars) ---------------------------------------------------- 1.2
Atmospheric composition ----------------------------- Hydrogen 83%, Helium 15%, Methane 2%

Voyager 2's Trajectory.
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Uranus' Rings

    In 1977, the first nine rings of Uranus were discovered.

    The outermost epsilon ring is composed mostly of ice boulders several feet across. A very tenuous distribution of fine dust also seems to be spread throughout the ring system.

    There may be a large number of narrow rings, or possibly incomplete rings or ring arcs, as small as 50 meters (160 feet) in width. The individual ring particles were found to be of low reflectivity. At least one ring, the epsilon, was found to be gray in color.

    The moons Cordelia and Ophelia act as shepherd satellites for the epsilon ring.

The ring structure.
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The following table summarizes the radius, mass, distance from the planet center, discoverer and the date of discovery of each of the moons of Uranus:
 

  
Moons of Uranus Discovered before Voyager 2.

• Summarised  information (Word 97 document)
• Information extracted from Britannica 97