When William Herschel discovered Uranus in 1781, it became the first planet to be discovered with a telescope. Unlike the inner planets and Jupiter and Saturn, Uranus was not in ancient times. Although it is the third largest planet, it is not easily visible to the naked eye because it is twice as far away from the earth as Saturn. Like Jupiter, Uranus is made up mostly of gas and like Saturn, it is circled by faintly visible rings. It takes Uranus 84 years to complete one revolution round the sun. Because of its greatly tilted axis of rotation, Uranus has the longest "summers" and "winters"- each lasting 42 years!
Uranus has five moons of its own. Voyager II, the spacecraft that visited Mars, Jupiter and Saturn earlier, photographed Uranus from close quarters in January 1986.