URANUS

Uranus was discovered in 1781. The seventh planet was named for the Greek son and husband of Gaea (Earth) and the father of Saturn and grandfather of Jupiter. Uranus is a huge planet with a diameter equal to four times Earth's diameter. Like the other gas giants, Uranus is also a ringworld. Its rings are dark and thin. Voyager 2 flew by Uranus in 1986 and detected 10 rings, but scientists think that as many as 100 fainter ones may exist. Unlike any other planets, Uranus spins on its side, with its poles facing toward and away from the Sun. One theory suggests that Uranus might have collided with an Earth-sized planet. The force of collision may have destroyed the small planet and knocked Uranus sideways. The atmosphere of Uranus is made up mainly of hydrogen and helium gases, with a small amount of methane gas, which gives the planet a bluish-green appearance. The atmosphere is quite clear, with some haze and a few clouds. Strong winds blow the blue-green gas around the planet. Near the planet's equator, winds have been clocked at speeds of nearly 650 miles per hour. One mystery discovered by Voyager 2 was that the sunlit pole of Uranus seems slightly cooler than the pole facing away from the Sun. Uranus has 21 moons. It takes Uranus 84 earth years to orbit the sun and a day on Uranus only lasts 16 hours and 48 minutes.