“ The comet that was visible in 1531, 1607, and 1682, would again be observed in 1758” - 1705 'A Synopsis of the Astronomy of Comets', in which he described the parabolic orbits of 24 comets that had been observed from 1337 to 1698.
Other Contributions He applied Newton's laws of motion to all available data and then mathematically demonstrated that comets move in elliptic orbits around the Sun in Astronomiae Cometicae Synopsis , and also wrote numerous treaties on trigonometry, planetary magnetism, optics, meteors, and orbital & celestial mechanics.
In 1720 Halley succeeded Flamsteed as astronomer royal at Greenwich, a position which he held until his death on 14 January 1742.
True or False 1. E. Halley was born on November 8, according to the Julian calendar. 2. In 1678 he published “Philosophiae Naturalis Principia Mathematica” 3. He was named Astronomer Royal, succeeding John Flamsteed. 4. The profecy that he made about the comet coming back came true. 5. Halley was appointed Savilian Professor of Geometry at Oxford University. 6. He died without any recognition on his work. (F) (F) (T) (T) (T) (F)