Sir William Herschel
Sir William Herschel, 1738–1822, born Friedrich Wilhelm Herschel, was a great pioneer in the study of the stars. Born in Hanover, Germany, the son of a musician, he early became a skilled performer on several instruments. He went to England in 1757 and worked as a musical conductor, organist, and teacher of music and studied mathematics and astronomy in his leisure time. He constructed telescopes and systematically explored the sky. On Mar. 13, 1781, he discovered a new planet later named Uranus. Because of this discovery he was appointed private astronomer to the king (1782), and was then able to devote his time to astronomy.
In 1789 at his home in Slough, Herschel erected his great telescope, with a 48-in. (122 cm) mirror and a focal length of 40 ft (12.2 m). Sir William discovered the sixth and seventh satellites of Saturn, determined the rotation period of Saturn, and studied the rotation of other planets. He concluded from the motions of double stars that they are held together by gravitation and that they revolve around a common center, thus confirming the universal nature of Newton's theory of gravitation. He cataloged over 800 double stars. His research in the field of nebulae suggested a possible beginning of new worlds from gaseous matter. Before this time only about 100 nebulae had been known; Sir William's catalog contained about 2,500. He concluded that the whole solar system is moving through space, and he was able to indicate the point toward which he believed it to be moving.
Caroline Lucretia Herschel
Sir William's sister, Caroline Lucretia Herschel, 1750–1848, discovered eight comets and three nebulae and from 1772 collaborated with her brother. She revised (1798) John Flamsteed's catalog of stars and arranged her brother's catalog of star clusters and nebulae, for which she received the gold medal of the Royal Astronomical Society in 1828.
Sir John Frederick William Herschel
Sir William's son, Sir John Frederick William Herschel, 1792–1871, first distinguished himself as a mathematician at Cambridge but later turned to astronomy. He confirmed his father's observations of double stars, was able to add numbers of previously unrecognized pairs to those in the catalog, and extended his examination to include nebulae. He presented his results to the Royal Society in the form of a catalog of stars in 1833. In order to complete the survey of the heavens, he went to the Cape of Good Hope in 1834 and discovered and measured many previously unseen nebulae and clusters of stars in the southern sky.
Among his books are Outlines of Astronomy (1849) and A General Catalogue of Nebulas (1864). The latter was revised by Johan Dreyer as A New General Catalogue of Nebulas and Clusters of Stars (1888), and, generally known as the NGC (see New General Catalog), it still serves as a standard reference source. Sir John also made contributions to the field of photography. He was the first to use sodium thiosulfate (hypo) as a fixing agent, and he introduced the terms “positive image” and “negative image.”
