- Views of the planet Uranus taken by the Voyager 2 spacecraft show the planet's blue color. In the …
The planet Uranus was the first to be discovered after the invention of the telescope. It is the seventh planet from the sun. The planet was named Uranus after the ancient Greek and Roman god of the heavens. Uranus orbits the sun at an average distance of about 1.8 billion miles (2.9 billion kilometers). Uranus is more than twice as far away from the sun as its neighbor Saturn. Uranus is one of the outer planets. Physical featuresUranus is the third largest planet in the solar system. Its diameter is about 32,000 miles (51,000 kilometers)—about four times that of the Earth. Uranus is most similar in size to Neptune, its outer neighbor. Like Jupiter, Saturn, and Neptune, Uranus is known as a gas giant because it is mostly made up of gases. Uranus is thought to have a core made of rock and ice that have been turned into liquid by the high pressures and temperatures of the interior of the planet. Surrounding this core is a layer of gases extending outward for hundreds of miles. Uranus' atmosphere is composed of gases—mostly hydrogen with some helium. It also contains clouds of methane ice. The methane is what gives Uranus its blue-green color. Weather and temperatureThe winds on Uranus are several times stronger than the winds on Earth. Although Uranus gets storms like the other gas giants, it does not seem to get as many. The average temperature in the cloud level is about −328° F (−200° C). RingsUranus has a system of narrow, sharp-edged rings made of some unusually dark material. These rings seem very unlike Saturn's bright, icy rings. Although the rings are thick in some places, in certain other places the rings are so thin that they disappear. Some scientists believe that Uranus' rings are young compared with Saturn's and are still being formed. Moons - A view of Ariel, a moon of the planet Uranus, shows numerous faults and valleys on the moon's …
- An image of Umbriel, a moon of the planet Uranus, shows the many craters on the moon's surface. The …
Uranus has at least 20 satellites, or moons. The five major ones are Oberon, Titania, Ariel, Umbriel, and Miranda. These five moons seem to be composed of ice and rock. Some have large craters. Others have deep canyons and other evidence that they may have once had activity similar to earthquakes and volcanic eruptions, though of icy materials rather than lava. Orbit and spinLike all planets, Uranus has two types of motion, known as orbit and spin. Uranus takes about 84 Earth years to orbit (travel around) the sun. Thus, one year on Uranus is equal to about 84 Earth years. Uranus' spin is very unusual. Like Venus, Uranus spins on its axis in a clockwise motion. Therefore, a person on Uranus would see the sun rise in the west and set in the east, which is the opposite of the Earth and most other planets. Uranus is also tilted in such a way that it spins on its side. It completes one rotation—and one day—in about 17 hours. (For more information on orbit and spin, see planets.) Observation and explorationUntil the 18th century, only the six innermost planets of the solar system were known, including the Earth. This is because these planets can all be easily seen from Earth without the use of a telescope. In 1781 astronomer William Herschel discovered Uranus while making a survey of the skies through his telescope. Uranus' rings were discovered in 1977 when an astronomer observed that something around Uranus blocked out a bright star as Uranus passed in front of it. Only one spacecraft has visited the distant planet. The United States National Aeronautics and Space Administration (NASA) launched Voyager 2 in 1977 to study several planets. It flew by Uranus and passed through its rings in 1986. Voyager collected data about many aspects of the planet, including its rings and interior. Photographs from the spacecraft showed weather patterns in the atmosphere and revealed several new moons as well. |