Herschel, (Frederick) William (1738-1822)

German-born astronomer William Herschel in 1781, the year in which he made his reputation by the discovery of Uranus, the first new planet to be identified for centuries. Herschel made his own telescopes and his early studies in astronomy drew him to the attention of George III, king of Great Britain and Ireland, who employed Herschel as his private astronomer.

German-born English astronomer. He was a skilled telescopemaker, and pioneered the study of binary stars and nebulae. He discovered the planet Uranus in 1781 and infrared solar rays in 1801. He catalogued over 800 double stars, and found over 2,500 nebulae, catalogued by his sister Caroline Herschel; this work was continued by his son John Herschel. By studying the distribution of stars, William established the basic form of our Galaxy, the Milky Way. He was knighted in 1816.

Herschel discovered the motion of binary stars around one another, and recorded it in his Motion of the Solar System in Space (1783). In 1789 he built, in Slough, a 1.2-m/4-ft telescope of 12 m/40 ft focal length (the largest in the world at the time), but he made most use of a more satisfactory 46-cm/18-in instrument. He discovered two satellites of Uranus and two of Saturn.

Herschel was born in Hannover. His father was a musician in the army. Following the same profession from 14, at the beginning of the Seven Years' War, in 1756, he was in the regimental band of the Hanoverian Guards. He left the army in 1757 and made his way to England, where he worked as a music teacher. His interest in the theory of harmony led him to mathematics and thence to optics, telescopes, and, about 1772, when his sister Caroline joined him from Hannover, to astronomy. The discovery of Uranus brought him fame and, in 1782, the post of private astronomer to George III. He and his sister left Bath that year to devote themselves to astronomy, first at Datchet, then at Old Windsor, and finally, in 1786, at Slough. Here at Observatory House, Herschel spent the rest of his life. In 1788 he married the widow of a wealthy London merchant and their only son, John Frederick William, was born four years later. In 1800, Herschel examined the solar spectrum using prisms and temperature-measuring equipment, and found that the hottest radiation was infrared. This was the beginning of the science of stellar photometry. He also established the motion and velocity of the Sun.