(After Jupiter and Saturn).
Mass And Gravity:
Uranus mass is about 8.68 x 10 Kg. This is about 14 times the mass of the Earth. The gravity on Uranus is only 91% of the gravity on Earth. This is because it is such a large planet (and the gravitational force a planet exerts upon an object at the planet’s surface is proportional to its mass and to the inverse of its radius squared). A hundred
-Pound person on Uranus would weigh 91 pounds.
Length Of A Day And Year On Uranus:
Each day on Uranus takes 17.9 Earth hours. A year on Uranus takes 84.07 Earth years; it takes 84.07 Earth years for Uranus to orbit the Sun once.
Uranus’s Orbit And Distance From the Sun:
Uranus is over 19 times as far from he Sun as the Earth is; it averages 19.18 A.U.
Temperature:
The mean temperature on the surface of Uranus’s cloud layer is –350*F (59 K)> Uranus radiates very little heat in comparison with the other gas giants, Jupiter, Saturn and Neptune.
Planetary Composition And Atmosphere:
Uranus is a frozen, gaseous planet with a molten core. Uranus’s atmosphere consists of 83% hydrogen, 15% helium and 2% methane.
Rings:
Uranus has a belt of 11 faint, narrow rings composed of rock and dust. They circle Uranus in very elliptical orbits. These rings are only a fraction of the size of Saturn’s rings, and were only discovered in 1977.
Moons:
Uranus has 5 large moons (2 were discovered by Wm.Herschel in 1781, 2 were discovered by Wm. Lassell in 1851, and one by G>Kuiper in 1948) and 13 small moons (which were discovered much later).
Discovery Of Uranus:
Uranus was discovered by the British astronomer William Herschel on 13th March 1781and named for the ancient Greek god of the sky. Herschel also discovered two of the moons of Uranus (Titania and Oberon) and some of the moons of Saturn.
Uranus’s Rotational Tilt And Extreme Seasons:
Uranus’s rotational axis is strongly tilted on its side (97.9*). Instead of rotating with its axis roughly perpendicular to the plane of its orbit (like all the other planets in our Solar System), Uranus rotates on its side (along its orbital path). This tipped rotational axis gives rise to extreme seasons on Uranus. A collision with another large body may have tipped Uranus over on its side.
Planetary Composition And Atmosphere:
Uranus is a frozen, gaseous planet. The planet is shrouded in an icy cloud layer (made up of frozen methane, ethane, and acetylene) circling this planet at 185 mph
(300 kph.) . Uranus’s icy atmosphere consists of 83% hydrogen, 15% helium and 2% methane. The outer layers of the atmosphere are the coldest; temperature and pressure rise under the cloud layer.
Partially-solid Layers:
Beneath the atmosphere, thee are a liquid layer of hydrogen and helium. As depth increases, this layer becomes more viscous, and then partly solid. This layer may be composed of compressed water with ammonia and methane.
Core:
Uranus has a molten core about 10,500 miles (17,00 Km) in diameter and about 12,500*F (6927*C). This core may have a mass five times greater than the mass of the Earth.
Spacecraft Visits:
NASA’S Voyager 2, whose closest approach was on, has visited Uranus
24th January 1986.
