1656-1742. English scientist. In 1682 he
observed the comet named after him,
predicting that it would return 1759.
Halley's other astronomical achievements
include the discovery that stars have their
own proper motion. He was a pioneer
geophysicist and meteorologist and worked in
many other fields including mathematics. He
became the second Astronomer Royal 1720. He
was a friend of Isaac Newton, whose Principia
he financed.