Sir Wilhelm Friedrich Herschel (November 15, 1738 Hanover - August 25, 1822 Windsor) was a German-born astronomer and composer who became famous for discovering the planet Uranus, and made many other astronomical discoveries.
Herschel was born as Friedrich Wilhelm Herschel in Hanover, Germany, one of ten children (of which four died very young). In 1755 the Hanoverian Guards regiment in whose band William and his brother Jacob were engaged was ordered to England. At the time, the crowns of England and Hanover were united under George II. He learned English quickly and, at age nineteen, he changed his name to Frederick William Herschel.
He became a successful music teacher and bandleader, played the organ and the oboe, and composed numerous musical works, most of which are largely forgotten today. He became Director of Public Concerts in Bath. His sister Caroline also came to England and lived with him.
His interest in astronomy grew stronger after 1773, and he built some telescopes and made the acquaintance of Nevil Maskelyne. He observed the Moon, measuring the heights of lunar mountains, and also worked on a catalog of double stars.
The turning point in his life was March 13, 1781, while residing at 19 New King Street, Bath, when he discovered Uranus. This made him famous and enabled him to turn to astronomy full-time. Naming the new planet Georgium Sidus in honour of King George III also brought him favour (the name didn't stick). That same year, Herschel was awarded the Copley Medal and was elected a Fellow of the Royal Society. In 1782, he was appointed "The King’s Astronomer" and he and his sister subsequently moved to Datchet (then in Buckinghamshire but now in Berkshire) on August 1, 1782. He also continued his work as a telescope maker, selling a number of them to other astronomers.
In 1783 he gave Caroline a telescope and she began to make astronomical discoveries in her own right, particularly comets. Caroline also served as his full-time assistant, taking notes while he observed at the telescope.
In June 1785, due to damp conditions, he and Caroline moved to Clay Hall in Old Windsor, and on April 3, 1786, they moved to a new residence on Windsor Road in Slough. William Herschel lived the rest of his life in this residence, which came to be known as Observatory House. It is no longer standing, having been demolished in 1963 to make way for a high-rise office building.
On May 7, 1788, he married the widow Mary Pitt (née Baldwin) at St Laurence's Church, Upton, near Slough. His sister Caroline then moved to separate lodgings, but continued to work as his assistant.
On August 28, 1789, he erected his renowned 40 ft (focal length), 48 in aperture, telescope, discovering a new moon of Saturn on the very first night's observation, and a second moon within the first month of observation. The 40 ft telescope proved very cumbersome, however, and most of his observations were done with a smaller telescope of 20 ft focal length.
William and Mary had one child, John, born at Observatory House on March 7, 1792. In 1816, William was knighted "Sir William Herschel" by the Prince Regent. He helped to found the Astronomical Society of London in 1820, which in 1831 received a royal charter and became the Royal Astronomical Society.
On August 25, 1822, Herschel died at Observatory House and is buried at nearby St Laurence's Church, Upton.
His son John Herschel also became a famous astronomer. One of William's brothers, Alexander, also moved permanently to England, near Caroline and William though not in the same household, but was not a scientist.
His house in Bath, where he made many telescopes and first observed Uranus, is now home to the William Herschel Museum.
Other astronomical work
In his later career, Herschel discovered two satellites of Saturn, Mimas and Enceladus; as well as two satellites of Uranus, Titania and Oberon. He did not give these satellites their names; rather, they were named by his son John in 1847 and 1852, respectively, well after his death.
He also worked on creating an extensive catalog of nebulas. He also continued to work on double stars, and was the first to discover that most double stars are not mere optical doubles as had been supposed previously, but are true binary stars.
He also discovered infrared radiation (ca. 1800).
From studying the proper motion of stars, he was the first to realize that the solar system is moving through space, and he determined the approximate direction of that movement. He also studied the structure of the Milky Way and concluded that it was in the shape of a disk.
He also coined the word "asteroid", meaning star-like (from the Greek asteroeides, aster "star" + -eidos "form, shape"), in 1802 (shortly after Olbers discovered the second minor planet, 2 Pallas, in late March of the same year), to describe the star-like appearance of the small moons of the giant planets and of the minor planets; the planets all show discs, by comparison.
Despite his numerous important scientific discoveries, Herschel was not averse to wild speculation. In particular, he believed every planet was inhabited, even the Sun: he believed that the Sun had a cool, solid surface protected from its hot atmosphere by an opaque layer of cloud, and that a race of beings adapted to their strange environment lived there.
Discovery of infrared radiation
Herschel discovered infrared radiation by passing sunlight through a prism and holding a thermometer just beyond the red end of the visible spectrum. The thermometer indicated a temperature increase and this led to Herschel's conclusion that there must be an invisible form of light.
Named after Herschel
- William Herschel's Deep Sky Catalog (http://www.seds.org/messier/xtra/similar/herschel.html)
- Full text of The Story of the Herschels (http://www.gutenberg.net/etext/12340) (1886) from Project Gutenberg
- Biography: JRASC 74 (1980) 134 (http://adsabs.harvard.edu//full/seri/JRASC/0074//0000134.000.html)