William Herschel
William Herschel was an influential astronomer and musician, renowned for his significant contributions to the field of astronomy in the late 18th and early 19th centuries. Born in Germany, he was the son of a skilled musician and developed a passion for music, mathematics, and astronomy from a young age. He moved to England in 1755 and initially pursued a successful career as a musician, eventually becoming an organist in Bath. Herschel's interest in astronomy intensified after acquiring a small telescope, prompting him to build larger telescopes for observation, including an impressive 20-foot model.
Herschel is best known for discovering the planet Uranus and its moons, which earned him a prestigious reputation and royal patronage. He made groundbreaking observations of celestial bodies, including detailed studies of comets, nebulae, and the Sun, and he is credited with coining the term "asteroids." Throughout his career, Herschel collaborated closely with his sister Caroline, who played a vital role in his astronomical endeavors. His meticulous observations and innovative telescope designs greatly expanded the understanding of the universe during his time. Herschel's legacy lives on, commemorated by various celestial formations and observatories named in his honor, including the upcoming Herschel Space Observatory.
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William Herschel
German-born English astronomer
- Born: November 15, 1738
- Birthplace: Hanover (now in Germany)
- Died: August 25, 1822
- Place of death: Slough, Buckinghamshire, England
Herschel discovered Uranus and six of its moons. Using several large telescopes that he designed and manufactured, he made numerous planetary observations and also discovered that the Milky Way has a cloud-like appearance because of its numerous distant stars. He also identified double and triple stars, nebulae, star clusters, and other celestial objects, and made detailed studies of the structure of comets and the surface of the Sun.
Early Life
William Herschel was one of six surviving children of Isaac and Anna Ilse Herschel. Isaac was a skilled musician and professor of music, and his talents seemed to have passed to several of his children, including William, who studied oboe, violin, and organ. William also loved mathematics and gained an interest in astronomy from his father.
In 1755, William and his brother Jacob, members of the Hanoverian regimental band, traveled to England when their regiment was ordered there. Initially, William’s pay was barely enough to avoid poverty, but as his musical abilities gained recognition he was invited to be bandmaster in a militia regiment in northern England. He forged relationships with wealthy families in the area, which led to even more musical involvement, including teaching instrument lessons, and to better fortunes.
In 1764, Herschel paid a brief visit to his family in Germany. Upon his return to England in 1765 he was appointed organist at Halifax, further securing his economic fortunes. Within a year he moved up to the more lucrative position of organist at the Octagon Chapel in Bath. His sister Caroline Lucretia Herschel joined him in 1772. By this time William Herschel’s life was extremely busy. What most would have considered a heavy, full-time job as a talented and popular musician was supplemented in Herschel’s case with his pursuit of mathematics.
Life’s Work
Soon after receiving a small telescope, William Herschel began the work that would gradually consume him for the rest of his life. His new thirst for exploring the night sky led him to build a larger telescope, since ready-made models were too expensive. After studying optics and experimenting with lens and mirror production, he settled on making an 18- to 20-foot telescope.
Soon Herschel’s obsession consumed not only much of his free time but also several rooms of the house that were converted into workshops. Caroline, along with brother Alex, were also drafted to work on his projects. All of this activity was taking place amid Herschel’s numerous musical responsibilities. His fixation on completing the 20-foot telescope was so intense that he would not stop turning a lens to eat, and Caroline often fed him or read to him while he worked. However, she was not simply a secretary and helpmate; she was also was an astronomer in her own right, and she possessed many of the observational and mathematical skills of her brother.
On the night of March 13, 1781, Herschel discovered the planet Uranus, initially named Georgium Sidus in honor of King George III. Consequently, he was awarded the Copley Medal and was elected a fellow in the Royal Society. The following year George III appointed him King’s Astronomer and awarded him an annual pension of 300 guineas and a home nearer the king. With a steady, dependable income, Herschel finally made a permanent switch to astronomy, resigning his post as organist at Bath.
Herschel’s next major project was to construct a more powerful 40-foot telescope. He eventually received funding of œ2,000, and, by 1786, he and his sister had moved to Slough, where he built a better observatory and began constructing a larger telescope. Because of the size and great weight of this larger telescope, everything about it had to be specially designed. The end product was so cumbersome that Herschel needed assistance to adjust it for viewing specific portions of the sky. Caroline continued to assist him, devoting her life to his work. She was his primary record keeper, spending most nights by his side at the telescope. Because of Herschel’s growing popularity, King George also provided funds to hire work assistants, who also gave tours to the growing numbers of visitors who came to see the large telescope and observatory.
Herschel’s primary interest was in the planets, but he also made observations of the Sun and developed theories about its surface appearance. He performed experiments using a prism to separate sunlight into its component colors, measuring the temperature of each. As a result, he discovered infrared radiation—invisible rays beyond the red end of the spectrum—and showed they possessed heat.
He observed the surface of the Moon in great detail and attempted to measure the height of some of its surface features. He believed that some of the Moon’s bright spots were volcanoes, a theory now known to be incorrect. He determined the shapes and approximate sizes of several of the “minor” planets, and believed that they were too small to be planets. He coined the term “asteroids” for these bodies, a name still used. He made detailed observations of comets, noting especially their nuclei and the apparent production of their own light.
In 1788 he married a woman with a large inheritance, which enabled him to devote his time completely to astronomy. His new marriage briefly strained his relationship with his sister. She moved out for a time but later rejoined the household and continued her work with Herschel.
Herschel was awarded an honorary degree from Oxford, and in 1816 he was knighted, becoming Sir William Herschel. In 1820 he was elected the first president of the Astronomical Society. By this point Herschel’s health was beginning to fail; he died on August 25, 1822. Both Caroline and Herschel’s son John carried on his work after his death, preparing a number of his documents for posthumous publication.
Significance
William Herschel has taken his place among the great astronomers primarily because of his discovery of Uranus and six of its moons. His meticulous nature, both as an observer and as a telescope-builder, helped him in his discoveries. His lesser-known, though no less important, discoveries stem from these same, almost obsessive, tendencies. It is fair to say that his successes also lay in large part with his sister, Caroline. Her devotion to his work, along with her own abilities in astronomy and mathematics, enabled him to accomplish much more than he might have on his own.
Herschel’s superior telescopes also helped him see objects never before observed by other astronomers. Most notable was his discovery that many hazy objects in the sky are actually groups of stars, often with clouds of gas accompanying them (nebulae). He discovered many nebulae and showed that the Milky Way is composed of millions of stars. Some of his speculations, however, about the Moon, the Sun, and the planets have not withstood the test of time. One of his wildest speculations was that all planets, and even the Sun, were inhabited.
Herschel’s work has been commemorated by several objects bearing his name, including a crater on the Moon and one on Mimas, a moon of Saturn; a large impact basin on Mars; and an asteroid. The William Herschel telescope, located in La Palma on the Canary Islands, also bears his name. In 2007 the European Space Agency plans to launch the Herschel Space Observatory, which will be the largest space telescope of its kind.
Bibliography
Armitage, Angus. William Herschel. Garden City, N.Y.: Doubleday, 1963. A biography of William Herschel focusing on his musical as well as his astronomical work.
Dreyer, John Luis Emil, ed. The Scientific Papers of Sir William Herschel. Bristol, England: Thoemmes Continuum, 2003. A collection of previously unpublished papers edited under the direction of a joint committee of the Royal Society and the Royal Astronomical Society. Includes a brief introductory biography.
Hoskin, Michael A. William Herschel and the Construction of the Heavens. London: Oldbourne, 1963. A biography of William Herschel focusing primarily on his astronomical work.
Lubbock, Constance A. The Herschel Chronicle: The Life-Story of William Herschel and His Sister, Caroline Herschel. Cambridge, England: Cambridge University Press, 1933. A more personal biography of Herschel and his sister, with material drawn from their respective records.