World Book at NASA for Students
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Image to left: Uranus is a giant blue-green planet. Credit: NASA
Uranus is a giant ball of gas and liquid. It is about four times the size of Earth. Scientists believe that the surface of Uranus is made up of blue-green clouds of methane, a gas. Beneath the surface are thick layers of water mixed with another gas called ammonia. The center of the planet may be a rocky core, just like Earth's. Scientists do not think there is any life on Uranus.
Uranus was the first planet discovered since ancient times. William Herschel discovered it in 1781. Herschel was a British astronomer, a scientist who studies planets and stars. Scientists have learned much about Uranus from the flight of the United States spacecraft Voyager 2. The spacecraft flew close to Uranus and took pictures. It sent these pictures back to Earth.
Uranus moves around the sun in an oval path. It takes about 84 Earth years for Uranus to go around the sun. (It takes one year for Earth to go around the sun.) Like Earth, Uranus also slowly spins on its axis, a make-believe line through the center of the planet. Uranus takes 17 hours and 14 minutes to spin once all the way around on its axis.
How to cite this article: To cite this article, World Book recommends the following format: "Uranus." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.
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