Halley was the first man to recognize the recurring astronomical visitor now known as Halley's Comet. Halley was already interested in the stars when he entered Queen's College, Oxford at the age of 16. He later left Oxford without a degree and became a protege of the Astronomer Royal, John Flamsteed. Halley and Flamsteed had a falling out, but by age 22 Halley had already been elected to the prestigious Royal Society. In 1705 he published Synopsis on Cometary Astronomy, in which he argued that prominent comets observed in 1531, 1607 and 1682 had all been the same comet, returning to pass Earth on a cycle of about 76 years. He was proven correct when the comet returned on Christmas Day of 1758 (though Halley himself had died in 1742), and the comet has since been known as Halley's Comet. Halley became a professor at Oxford in 1704 and succeeded Flamsteed as Astronomer Royal in 1720. Multitalented and exceedingly brainy, Halley also contributed to other scientific fields during his long career; he is especially known for inventing the diving bell.