Edmond Halley

Edmond Halley was an English astronomer, mathematician and the second Astronomer Royal, best known for using Newton's law of universal gravitation to compute the orbit of the comet now named after him and to correctly predict its return, a prediction published in his 1705 Synopsis of the Astronomy of Comets and confirmed in 1758, sixteen years after his own death. Elected a Fellow of the Royal Society in 1678 at the age of twenty two, he spent a year on the South Atlantic island of Saint Helena compiling the first telescopic catalogue of the southern sky. He is also credited with discovering the proper motion of stars in 1718, by comparing his own observations against the ancient positions recorded by Ptolemy, and with pioneering the use of isogonic lines on maps from his magnetic declination surveys. Halley personally read, championed and paid the printing costs of Isaac Newton's Philosophiae Naturalis Principia Mathematica, without which the 1687 work might not have been published at all. He served as the second Astronomer Royal at the Royal Observatory, Greenwich from 1720 until his death in 1742.