Herschel, William

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Herschel, William (1738-1822): English Astronomer.

A German emigre, William Herschel founded one of England's leading scientific families and came to be synonymous with Enlightenment observational astronomy. A musician by training, Herschel fled Hanover, Germany, following its capture by the French in 1757. In 1766, he settled in Bath and became organist at the Octagon Chapel. In his spare time, his independent studies led him to an interest in the field of optics, culminating in his fascination with the construction of telescopes.

From the beginning, Herschel's interest lay in deep sky objects as opposed to the more frequently observed objects of our own solar system, an orientation that would drive his "bigger is better" philosophy of telescope design due to the demands of light-gathering required for viewing such distant objects. This quest would culminate in 1789 with the completion of his 40-foot long, 48-inch diameter reflecting telescope at Slough.

In 1799, Herschel initiated his first review of the night sky, concentrating on the discovery of binary or "double star" systems. It was during this project that, on 13 March 1781, he discovered the planet Uranus, giving him the distinction of being the first person to discover a major planet since antiquity. The acclaim that followed was worldwide and lasting, much more so than the name Herschel proposed for the new world: Georgium Sidus ("the Georgian planet") in honor of George III. J. E. Bode would propose the moniker that was ultimately accepted.

As a result of his discovery, Herschel received an annual pension from the crown the following year, which allowed him to resign his musical post and pursue astronomy full time. Various breakthroughs would result from the years of meticulous observation that followed. Among them was his discovery of the motion of double stars as explained by their mutual gravitational attraction, thus verifying Newton's law of universal gravitation. Also, having previously confirmed that stellar nebulae (i.e., galaxies) consist, upon close resolution, of individual stars, Herschel's discovery on 13 November 1790 of an exception to that rule, in the form of the planetary nebula NGC 1514 (a star surrounded by a envelope of glowing gas from which it coalesced) confirmed the nebular hypothesis of stellar evolution of Kant, Immanuel and Laplace, Pierre Simon de.

Herschel's enduring contribution to the world of science is two-fold. First, there is the work, which manifests both the limits and possibilities of purely observational astronomy. Herschel was clearly out of his element whenever called upon to theorize outside the arena of speculations intimately and inextricably linked to established observational facts. Still, the quantity and quality of his contribution to the body of such observational knowledge is staggering given the day and age.

Secondly, Herschel must be remembered as the patriarch of an eminent scientific family, which includes his sister, and tireless secretary, Caroline Herschel (1750-1848), who merits mention as an astronomer in her own right, and his son, John Frederick William Herschel (1792-1871), whose achievements in the observational astronomy of the southern hemisphere rival those of his father in the north.

Further Reading:

Michael A Hoskin, William Herschel and the Construction of the Heavens, 1964.

Tom Call

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