Occupation: Astronomer & Musician
Year born: 1738
Research Areas: Astronomy, Radiation
"I have made it a rule never to employ a larger telescope when a smaller will answer the purpose."
Source: Sir William Herschel His Life and Works, Charles Scribner’s Sons, New York USA.
William was born in Germany. His father played the oboe in a military band. Aged 19, William moved to England and taught music. In 1772, his sister Caroline joined him to train as a singer. During this time, William became more interested in astronomy. He rented a small telescope but dreamed of having his own observatory. William learned how to build a large telescope, grinding and polishing the mirrors himself. He completed his first telescope in 1774.
William spent nine years carrying out surveys of the night-sky and published his own star catalogues. One night observing through his telescope, William realised that one object was not a star, but a planet. William had discovered Uranus. This was the first planet discovered since ancient times, and its discovery made William famous overnight. King George III immediately made William the Royal Astronomer. He became a Fellow of the Royal Society and was given money for the construction of new telescopes.
William is reported to have cast, ground, and polished more than four hundred mirrors for telescopes. The largest and most famous telescope he built, was 12 metres in length. At the time, it was the largest scientific instrument in the world. Telescopes that use William’s design are called ‘Herschelian’.
William’s other work included determining the rotation period of Mars, observing the Martian polar caps, and discovering the moons Titania and Oberon (of Uranus), and Enceladus and Mimas (of Saturn). William pioneered the use of 'spectrophotometry' in astronomical observations. This involved using prisms and temperature probes to measure the spectrum of light coming from stars. He discovered infrared radiation during these experiments, by observing its effect on a thermometer.
William was the first President of the Royal Astronomical Society. He died in 1822, and his work was continued by his only son, John Herschel. His house in Bath, Somerset, where he made many telescopes and first observed Uranus, is the Herschel Museum of Astronomy. The William Herschel Telescope is named after him.
William trained as a musician as a child. He played the oboe, violin, harpsichord, and organ. He composed 24 symphonies as well as church music.