(1656-1742) English atronomer who not only identified 1705 the comet that was later to be known by his name, but also compiled a star catalog, detected the proper motion of stars, using historical records, and began a line of research that—after his death—resulted in a reasonably accurate calculation of the astronomical unit.
Halley calculated that the cometary sightings reported in 1456, 1531, 1607, and 1682 all represented reappearances of the same comet. He reasoned that the comet would follow a parabolic path and announced 1705 that it would reappear 1758. When it did, public acclaim for the astronomer was such that his name was irrevocably attached to it.
Halley was also a pioneer geophysicist and meteorologist and worked in many other fields including mathematics. He was a friend of Isaac Newton, whose Principia he financed.
Halley was born near London and studied at Oxford but left without taking a degree. He spent 1676–78 on the S Atlantic island of St Helena, charting the stars of the southern hemisphere. He became professor of geometry at Oxford 1703.

Množina: Halley's comets

Comet that orbits the Sun about every 76 years, named for Edmond Halley who calculated its orbit. It is the brightest and most conspicuous of the periodic comets. Recorded sightings go back over 2,000 years. It travels around the Sun in the opposite direction to the planets. Its orbit is inclined at almost 20º to the main plane of the Solar System and ranges between the orbits of Venus and Neptune. It will next reappear 2061.
The comet was studied by space probes at its last appearance 1986. The European probe Giotto showed that the nucleus of Halley’s comet is a tiny and irregularly shaped chunk of ice, measuring some 15 km/10 m long by 8 km/5 m wide, coated by a layer of very dark material, thought to be composed of carbon-rich compounds. This surface coating has a very low albedo, reflecting just 4% of the light it receives from the Sun. Although the comet is one of the darkest objects known, it has a glowing head and tail produced by jets of gas from fissures in the outer dust layer. These vents cover 10% of the total surface area and become active only when exposed to the Sun. The force of these jets affects the speed of the comet’s travel in its orbit.