Edmond Halley

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Edmond Halley (1656–1742)

Edmond (el. Edmund) Halley (29. oktober 1656–14. januar 1742) var ein engelsk astronom, geofysikar, matematikar, meteorolog og fysikar.

[endre] Liv og karriere

Halley var son av ein rik såpemakar og blei fødd i Haggerston i London. Han gjekk på St Paul's School og var frå 1673 student ved The Queen's College i Oxford. Allereie før han tok noka grad gav han ut artiklar om solsystemet og solflekkar.

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On leaving Oxford, in 1676, he visited the south Atlantic island of St. Helena with the intention of studying stars from the Southern Hemisphere. He returned to England in November 1678. In the following year he published Catalogus Stellarum Australium which included details of 341 southern stars. These additions to the star map earned him comparison with Tycho Brahe. He was awarded his MA degree at Oxford and elected as a Fellow of the Royal Society.

In 1686 Halley published the second part of his expedition, being a paper and chart on trade winds and monsoons. In this he identified solar heating as the cause of atmospheric motions. He also established the relationship between baromatic pressure and height above sea level.

Halley married in 1682 and settled in Islington. He spent most of his time on lunar observations, but was also interested in the problems of gravity. One problem that attracted his attention was the proof of Kepler's laws of planetary motion. In August 1684 he went to Cambridge to discuss this with Isaac Newton, only to find that Newton had solved the problem but published nothing. Halley convinced him to write the Principia Mathematica Philosophiae Naturalis (1687), which was published at Halley's expense.

In 1693 he published an article on life annuities, which featured an analysis of age-at-death taken from the records of Breslau, a Polish-German town known for keeping meticulous records. This allowed the British government to sell life annuities at an appropriate price based on the age of the purchaser. Halley's work strongly influenced the development of actuarial science. The construction of the life-table for Breslau, which followed more primitive work by John Graunt, is now seen as a major event in the history of demography.

In 1690 he completed plans for a diving bell, an apparatus capable of remaining submerged for extended periods of time, and fitted with a window for the purpose of undersea exploration. In Halley's diving bell, atmosphere is replenished by sending weighted barrels of air down from the surface.

In 1698 he received a commission as captain of HMS Paramore to make extensive observations on the conditions of terrestrial magnetism. This task he accomplished in an Atlantic voyage which lasted two years, and extended from 52 degrees north to 52 degrees south. The results were published in a General Chart of the Variation of the Compass (1701). This was the first such chart to be published and the first on which isogonic lines, or, as they were called, Halleyan lines, appeared.

In November 1703 he was appointed Savilian professor of geometry at Oxford University, and received an honorary degree of doctor of laws in 1710. In 1705 he published Synopsis Astronomia Cometicae, which stated his belief that the comet sightings of 1456, 1531, 1607 and 1682 related to the same comet, which he predicted would return in 1758. When it did it became generally known as Halley's Comet.

In 1716 Halley suggested a high-precision measurement of the distance between the Earth and the Sun by timing the transit of Venus. In 1718 he discovered the proper motion of the "fixed" stars by comparing his astrometric measurements with those of the Greeks.

In 1720, Halley succeeded John Flamsteed as Astronomer Royal, a position which he held until his death. He was buried at St. Margaret's Church in Lee in south-east London. -->