Uranus is the seventh planet out from the Sun in the Solar System and the first planet to be discovered following the invention of the telescope. This discovery was made accidentally by the German-born English astronomer William Herschel in 1781 during a routine sky survey at his observatory in Bath. On March 13, in that year he came across an object that looked decidedly unstarlike in appearance, and an observation made a few nights later showed that its position against the background stars had altered. This led Herschel to believe, initially, that he had discovered a comet, but prolonged observation of its orbital motion brought astronomers to the conclusion that the object was in face a planet. The German astronomer J.E. Bode suggested the name Uranus, in honor of the ancient sky god who in Greco-Roman mythology was the father of Saturn.
Uranus is a strange greenish-blue world a little larger than the planet Neptune, which it resembles closely. Like Jupiter, Saturn, and Neptune, Uranus is classed as one of the giant planets.
Uranus is some 51,000 kilometers (31,700 miles) in diameter, almost four times the size of Earth. It takes almost exactly 84 years to travel once around the Sun, orbiting it at an average distance of nearly 2 billion 870 million kilometers (1 billion 783 million miles). This puts Uranus twice as far away from the Sun as Saturn is.
© 1988 Encyclopaedia Britannica, Inc.