Discovery of Uranus

Sir William Herschel (1738-1822)

The planet Uranus was discovered by the noted British astronomer, Sir William Herschel, on March 13, 1781. Actually, the planet had been observed numerous times by other astronomers as early as 1690, but it was thought to be another star.

The planet was discovered accidentally while Herschel was surveying all stars down to magnitude eight -- those that are about ten times dimmer than can be seen by the naked eye. One "star" seemed different and within a year was shown to have a planetary orbit 18 times farther from the Sun than Earth. The new planet was named Uranus after the father of Saturn in Roman mythology.

Uranus was discovered using this 15-centimeter (6-inch) telescope designed and built by Herschel.

William Herschel built his own telescopes , including one which had a focal length of 6 meters (20 feet) and a larger telescope of the same design with a 12 meter (40 foot) focal length.

Voyager image of Uranus and 3 of its moons.