Planet Uranus

Before 1781, scientists believed that the solar system held the sun and six planets. William Herschel was a German musician who lived in England. He became fascinated with astronomy. In his spare time, he decided to build his own telescope because he thought there were other bodies in the universe which had not been seen yet. He had 200 failures but finally produced a new higher-powered telescope.

He began to look again at all the objects in the heavens which he knew. One night, March 13, 1781, he saw a dim star in the constellation Gemini. Its size made him suspect that it was closer to Earth and really not part of the constellation. Its color was pale blue. At first, he thought it was a comet. After watching its movements, astronomers decided it was not a comet but a new planet, the first to be discovered since ancient times. According to tradition, the planet was named from Greek mythology, Uranus. He was the god of the heavens or sky and husband of Gaea, the earth. He was the father of Saturn.

Voyager 2 is a space probe which was designed by an international team. It did a flyby of Uranus in 1986 as it was studying the entire solar system. The plan was for this probe to fly farther and farther from Earth until it leaves the solar system sending back huge amounts of information on whatever it sees.

Uranus is the seventh planet from the sun. Uranus is a gas giant, like Jupiter, Saturn, and Neptune. It has no solid surface. The solid core of the planet is about the same size as Earth. A giant ocean surrounds the core. It is about 5,000 miles deep. It is mostly water with a little methane and ammonia added. It is different from Earth's oceans because its temperature is 8,000 degrees F. Because Uranus is so far from the sun, it maintains a cold surface temperature of -350°F. Even the part facing the sun seems to keep very cold.

At the surface of the ocean, the water turns into vapor and mixes with the thick layer of gas, mostly hydrogen, methane, and helium. Uranus' blue-green color comes from the methane. The layer of gas is about 4,000-5,000 miles deep. Because the layer of gas is so heavy, it pushes down on the ocean water and prevents it from boiling. The pressure causes the ocean to be electrically charged at the surface. A magnetic field is created around the planet.

Other planets in the solar system have magnetic fields also, but usually, they are at the poles. The magnetic field on Uranus is tilted sixty degrees off the axis. The poles on Uranus are not on the top and bottom like most planets but on the sides. The planet spins from the north to the south. Earth spins east to west.

As Uranus orbits the sun, each pole points once toward the sun. It gets forty-two years of sun and forty-two years of darkness. Each season takes twenty-one years. It spins on its axis every seventeen and one-quarter hours. This would be like a day. The planet travels through space at four and one-quarter miles per second. This speed is only one fourth that of Earth. Because Uranus is so far from the sun, it takes eighty-four Earth years to complete its orbit.

Uranus has thirteen narrow rings. They consist of dust and rocks. They circle the planet from top to bottom instead of around the middle like those of Saturn. The first was discovered in 1977. Others were found in 1986 by the spacecraft Voyager 2. The Hubble telescope found two new outer rings in 2003. Uranus has twenty-seven moons. Some take years to orbit because they are so far away.

A: 31
B: 42
C: 6
D: 27

A: 1943
B: 2003
C: 1781
D: 1986

A: Voyager 2
B: Mariner 2
C: Voyager 5
D: Hubble

A: Uranus spins from north to south.
B: Uranus spins from east to west.
C: Earth spins from east to west.
D: None of the above.

A: Hydrogen
B: Methane
C: Chloride
D: Oxygen

A: Saturn
B: Neptune
C: Earth
D: Uranus

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