Airy , Sir George Biddell

(1801–1892) British astronomer

Airy, the son of a tax collector, was born in Alnwick in the north-east of England. He attended school in Colchester before going to Cambridge University in 1819. He met with early success, producing a mathematical textbook in 1826 and numerous papers on optics. He became Lucasian Professor of Mathematics at Cambridge in 1826 and two years later was made Plumian Professor of Astronomy and director of the Cambridge Observatory. In 1835 he was appointed Astronomer Royal, a post he held for 46 years.

Airy was a very energetic, innovative, and successful Astronomer Royal. He re-equipped the observatory, installing an altazimuth for lunar observation in 1847, a new transit circle and zenith tube in 1851, and a 13-inch (33-cm) equatorial telescope in 1859. He created a magnetic and meteorological department in 1838, began spectroscopic investigations in 1868, and started keeping a daily record of sunspots with the Kew Observatory heliograph in 1873. In optics he investigated the use of cylindrical lenses to correct astigmatism (Airy was astigmatic) and examined the disklike image in the diffraction pattern of a point source of light (in an optical device with a central aperture) now called the Airy disk. Also named for him is his hypothesis of isostasy: the theory that mountain ranges must have root structures of lower density, proportional to their height, in order to maintain isostatic equilibrium.

Despite his many successes he is now mainly, and unfairly, remembered for his lapses. When John Adams came to him in September, 1845, with news of the position of a new planet, Airy unwisely ignored him, leaving it to others to win fame as the discoverers of Neptune. He also dismissed Michael Faraday's new field theory.