Uranus
Image of Uranus taken from the Hubble Space Telescope. You can see that the planet is tilted on its side. Image courtesy of http://nasa.gov
Uranus is one of the gas giants and is very large, but it is one and three quarter billion miles from the sun. It cannot be seen from Earth without a telescope. Uranus was discovered in 1781 by William Herschel, a German-born British astronomer who also discovered infrared radiation. Uranus was the first planet discovered by telescope. When Galileo looked at the sky with his telescope, he saw Uranus as well. He thought it was a star, so he does not get credited for discovering Uranus.
The newly discovered planet did not have a name right away. The six other planets had been named after Roman gods, and Uranus was finally named after a Greek god. Uranus was the Greek god of the sky and was the father of the god Saturn.
Uranus is one of the four gas giants. The most common gases in Uranus’ atmosphere are helium and hydrogen. It also contains methane. Under the atmosphere is an ocean made of water, ammonia and liquid methane. Scientists disagree about what is under this ocean. Some think it has a rocky core and others think there is no core.
Uranus is very cold and dark. It is very far from the sun so does not get very much light or heat from the sun. From Uranus, the sun looks much smaller and dimmer than here on Earth. The temperature can drop as far as -320 degrees Fahrenheit. The coldest temperature on Earth is -100 degrees Fahrenheit. Because of this, Uranus and Neptune are sometimes called “ice giants.”
Like the other giants, Uranus has rings but they are much smaller than the famous rings of Saturn. They are made of dust particles, ice and rocks that can be as large as boulders. Uranus also has at least 27 moons, all of which are named for characters in plays by William Shakespeare or Alexander Pope. Although Uranus has many moons, each one is small.
It takes Uranus 84 years to travel once around the sun. It spins fast, however, taking only 17 hours and 15 minutes to make one rotation on its axis. Even though it is much bigger than Earth, its days are much shorter. One interesting fact is that Uranus is the only planet in the solar system whose axis is horizontal. This means the planet is tilted on its side. Nobody knows why Uranus is tilted on its side except God. Some think it was hit by a comet or other large object. Others think it was just made that way. We cannot really know.
