Edmond Halley

Edmond Halley (1656–1742) sailed to St Helena as a young Oxford student in 1676, setting up an observatory to map 341 southern hemisphere stars. In 1684, visiting Cambridge to ask Newton about planetary orbits, he discovered that Newton had solved the physics of orbital ellipses, and generously financed and oversaw the publication of Newton's immortal Principia at his own expense.

Applying Newton's gravitational laws to historical cometary sightings, Halley recognized that the comets of 1531, 1607, and 1682 were appearances of the same periodic celestial traveler. In 1705, he boldly predicted its return in 1758; when the comet reappeared exactly as foretold, it was christened Halley's Comet. In geophysics, he created the first magnetic declination ocean charts.