Halley Predicts a Comet's Return

December 1, 1705

Edmond Halley, applying Newton's laws to historical records, calculated that the great comets of 1531, 1607, and 1682 were the same object on a seventy-six-year orbit. He predicted its return in 1758. He would not live to see it, but the comet, when it came, came on schedule. It was the first time science had foretold a celestial event decades in advance.