James Bradley

Bradley, James 

Born 1693 in Sherborne, Gloucestershire; died July 13, 1762, in Chalford, Gloucestershire. English astronomer; member of the London Royal Society (1718). Professor at Oxford University (1721).

Continuing the observations of the amateur astronomer S. Molyneux, which were intended to discover the annual parallax of stars, Bradley noticed a periodical shift of the star γ Draconis that was not accounted for by parallax; this led him to the discovery of the aberration of light (1725). He informed the London Royal Society of this in January 1729. He also discovered the nutation of the earth’s axis (1737), but he announced this discovery only in 1748, after he determined its period. After the death of E. Halley in 1742, Bradley became director of the Greenwich Observatory. In 1750 he began his meridional observations, which yielded material for determining continuous aberration, precession, and nutation; these observations long served to determine the movements of the stars.

REFERENCE

Berry, A. Kratkaia istoriia astronomii, 2nd ed. Moscow-Leningrad, 1946. (Translated from English.)