Edmond Halley

1656 - 1742

English astronomer and mathematician, savilian professor of geometry at Oxford.

First to detect the proper motion of stars.

Discovered the 76-year cycle comet that bears his name.

Edmond Halley was born on October 29, 1656 in the village of Haggerston, England. Today, this village is part of London. Halley was the son of a prosperous landowner. He eventually attended the St. Paul's school where he was appointed captain in 1671. It is a position similar to today's student body president. Halley did very well in school and attended the Queen's college in Oxford in 1673. He became a member of the Royal Society at the age of 22. Halley was appointed Savilian professor of geometry at Oxford in 1704. In 1720 he succeeded John Flamsteed as astronomer royal. Halley was an extremely talented scientist in many disciplines. He supported Isaac Newton both morally and financially, and was partly responsible for persuading him to publish his works.

From the island of Saint Helena, Halley cataloged the positions of around 350 Southern Hemisphere stars and observed a transit of Mercury. He believed that this phenomenon and future transits of Venus be used to determine the distance of the Sun. Halley also used the first transit instrument at the Greenwich Observatory and devised a method for determining longitude at sea by means of lunar observations. In 1710, comparing current star positions with those listed in Ptolemy's catalog, he deduced that the stars must have a slight motion of their own, and he detected this proper motion in three stars.

Halley also studied the Earth's weather and magnetic field as well as the ocean's tides, but is perhaps best known for his observations of the comet that bears his name. He was the first to notice that the comets of 1456, 1531, 1607, and 1682 followed similar paths around the Sun and that the appearance of each of these comets occurred about 76 years apart. This was precisely the period predicted for the comet's orbit by Kepler's Third Law. Halley correctly surmised that the appearances of these comets were due to the reappearance of the same object whose orbit brought it close to the Sun every 76 years. He also correctly predicted that the comets would appear again in 1758. Halley died in 1742, but the comet was indeed sighted in the sky on Christmas day in 1758. It has borne Halley's name ever since. More recent studies of this comet have found references to it dating back over 2000 years.