Edmund Halley's father was also called Edmund Halley. Halley made important observations at Oxford, including an occultation of Mars by the Moon on 21 August 1676, which he published in the Philosophical Transactions of the Royal Society. It is a little unclear what happened to Halley's undergraduate career, but what is certain is that he gave up his studies in 1676 and sailed to St Helena in the southern hemisphere in November of that year. The most likely explanation is that with the opening of the Royal Observatory at Greenwich in 1675, Flamsteed undertook the task of mapping the northern hemisphere stars and Halley decided to complement this program with undertaking a similar task for the southern hemisphere. From around 1695 Halley made a careful study of the orbits of comets. Newton favored comets having parabolic orbits, but Halley believed that elliptical orbits might exist. Using his theory of cometary orbits he calculated that the comet of 1682 now called Halley's comet was periodic and was the same object as the comet of 1531, and 1607. He later also identified this comet with one which appeared in 1305, 1380, and 1456. In 1705 he published his prediction that it would return in 76 years, claiming that it would appear in December 1758. It was not an easy calculation for Halley had to take into account the perturbations to the orbit produced by Jupiter. Although Halley had been dead for fifteen years by 1758, he achieved lasting fame when the comet was observed on 25 December 1758 very slightly later than Halley expected. Halley's other activities included studying archaeology, geophysics, the history of astronomy, and the solution of polynomial equations. He was an integral part of the English scientific community at the height of its creativity.