On this date in 1656, astronomer Edmund Halley was born in the United Kingdom. The Royal Society published a scientific paper by Halley when he was only 19. He cut short his college career to travel to St. Helena, the southernmost point of the British empire, where he cataloged 341 stars, discovered a star cluster, and made the first complete observation of a transit of Mercury. King Charles II conferred a degree from Oxford upon Halley without requiring an exam. At 22, Halley became one of the youngest members admitted to the Royal Society. He had worked with Astronomer Royal John Flamsteed at Oxford and Greenwich. Flamsteed became Halley's enemy and blocked his appointment to Oxford on account of Halley's rationalist views in 1691. Although not well off, Halley urged Newton to write his Principia Mathematica and published it for Newton. Halley remains famous for being the first to predict the return of a comet (named for him). After several posts, Halley finally secured a professorship at Oxford in 1703. When Flamsteed died, Halley became Royal Astronomer in 1720. He was known during his day as "the Infidel Mathematician." While not all his theories proved correct, Halley made many important discoveries, innovations and inventions, such as the diving bell. D. 1741.