Edmond Halley

Edmond Halley was an English astronomer, mathematician, and geophysicist best known for computing the orbit of the great comet that bears his name. While still an undergraduate at Oxford, he sailed to the island of St. Helena in the South Atlantic to catalog the stars of the southern sky — the first systematic southern star catalog produced by a European astronomer. His friendship with Isaac Newton proved pivotal to science: Halley personally funded the publication of Newton's Principia Mathematica in 1687. Applying Newton's gravitational theory to cometary orbits, Halley realized that the bright comets of 1531, 1607, and 1682 were the same object returning periodically, and predicted its return in 1758. The comet appeared on schedule, 16 years after Halley's death, and was named in his honor. He served as Astronomer Royal from 1720 until his death.

Predicted the periodic return of the comet now called Halley's Comet (confirmed 1758). Compiled the first catalog of southern hemisphere stars from St. Helena (1678). Funded and encouraged the publication of Newton's Principia Mathematica. Discovered the proper motion of stars by comparing contemporary positions with ancient catalogs. Proposed the transit of Venus method to measure the Earth-Sun distance (Astronomical Unit).