(1656 - 1742)English astronomer. A friend of Newton, Halley is best known for his study of comets. He concluded that the comets of 1531, 1607, and 1682 were in reality a single body and accurately predicted itsreturn in 1758. The comet has since been known as Halley's Comet. See also Isaac Newton in this glossary.—The Reader's Encyclopedia (Scientology and Ability Glossary) Final approval 18/9/89