- English atronomer
who not only identified 1705 the comet that was later to be known by
his name, but also compiled a star catalogue, 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 became the second Astronomer
Royal 1720. 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.