William Herschel (1738 - 1822) was a German-born British astronomer, telescope maker, and composer who in 1781 discovered the planet Uranus, the first planet identified with a telescope and the first found since antiquity. [1] Originally a professional musician, he became one of the most influential observational astronomers of his age, expanding the known boundaries of the Solar System and pioneering the study of deep-sky objects.
Early life and music
Born Friedrich Wilhelm Herschel in Hanover, then part of the Electorate of Hanover, he came from a musical family: his father was an oboist in the Hanoverian Guards band, and William trained as a musician from an early age. In 1757 he settled in England, where he worked as an organist and music teacher, eventually becoming organist at the Octagon Chapel in Bath. [2] His younger sister Caroline Herschel joined him in Bath and became his devoted assistant and an accomplished astronomer in her own right.
The discovery of Uranus
Herschel's growing interest in astronomy led him to construct his own reflecting telescopes, grinding and polishing mirrors of exceptional quality. On 13 March 1781, while surveying the sky from his garden in Bath, he observed an object he first took to be a comet. Continued observation showed it to be a new planet, which he named Georgium Sidus in honour of King George III; it was later renamed Uranus. The discovery effectively doubled the known size of the Solar System and brought him international fame.
Royal patronage and telescopes
King George III appointed Herschel as his personal astronomer, granting a pension that allowed him to devote himself fully to the science. He settled near Windsor and later in Slough, where he built ever-larger instruments, culminating in a reflector with a 40-foot focal length. Using such telescopes he discovered two moons of Uranus, Titania and Oberon, and two moons of Saturn, Mimas and Enceladus.
Wider contributions
Herschel undertook systematic surveys of the heavens, cataloguing thousands of nebulae and star clusters and studying binary stars. In 1800 he discovered infrared radiation while measuring the temperatures of the colours of sunlight split by a prism, detecting heating beyond the red end of the visible spectrum. [1] He was elected a Fellow of the Royal Society and awarded its Copley Medal in 1781.
Legacy
Herschel was knighted and, in 1820, became the first president of the Astronomical Society of London, later the Royal Astronomical Society. His son John Herschel and sister Caroline both became noted astronomers. Widely regarded as a founder of modern observational astronomy, he is commemorated in the names of craters, observatories, and the Herschel Space Observatory.
