Halley, Sir Edmund
(1656-1743)
Halley worked out the elliptical orbits of comets orbiting the Sun using Newton's Law of Planetary Motion.
The Amazing Discovery.
He discovered that one of the comets he observed in 1682 had the same orbit as the one seen in 1607. In a thrilling piece of detective work, he next tracked it back to 1531: the comet of that era was on the same orbit! Clearly, these three apparitions were of the same object. They named this comet after him and it is now known as Halley's Comet. He deduced that the comet returns every 76 years or so. Halley said it would come again in 1758, but unfortunately he did not live long enough to see it.