Edmond Halley was born near London, England in 1656. He discovered many things, however, most people recognize him as the discoverer of Halley's comet. In 1682, he used his theory of comet's orbits to figure out that the comet seen in 1682 was periodic. He predicted that the comet would return in seventy-six years. He also suggested using Mercury and Venus's orbits to determine the distance to the Sun. With Ptolemy's research, in 1710, he reasoned that stars have small movements and found these movements in three stars. On the island of Saint Helena, he mapped the positions of more than 350 stars. At the Greenwich Observatory, he used lunar observations to measure longitude at sea. Halley was a graduate of Oxford University and joined the Royal Society at age 22. In 1704, he became a professor of geometry and later earned the title of Astronomer Royal. He studied archeology and helped out at the mint in Chester. He was very involved in the scientific community and worked with many other astronomers. He died in 1742 in Greenwich, England.