Ganymede, a satellite of the planet Jupiter. With a diameter of 3,270 miles (5,260 km), Ganymede is the largest satellite in the solar system, and is larger than the planet Mercury. Its surface is composed of ice and has distinct dark and light areas. The dark areas are heavily cratered and the light areas are covered by long, parallel channels. Ganymede was discovered by Galileo Galilei in 1610.
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Uranus is the seventh planet from the sun, and is named for the ancient Greek deity of the Heavens, the earliest supreme god. It is the third largest planet in the solar system, and is three times as large as Earth.