Edmund Halley

Halley, Edmund (1656–1742), English astronomer. In 1677 he made the first full observation of a transit of Mercury and in 1676–79 prepared a major catalog of southern hemisphere stars. He encouraged Isaac Newton to write the Principia, whose publication he financed. In 1720 he succeeded John Flamsteed as astronomer royal. He is best known for his prediction that the comet of 1682 would return in 1758, based on Newton's calculations of the comet's elliptical orbit around the sun. When the prediction was born out, the comet was named after him.

See also: Astronomy.