एडमंड हैली (मृत्यु- 14 जनवरी, 1742)

January 14, 2017

एडमंड हैली (जन्म- 8 नवम्बर,1656, शोरडिच, इंग्लैंड; मृत्यु- 14 जनवरी, 1742, ग्रीनविच, यूनाइटेड किंगडम) प्रसिद्घ खगोलशास्त्री थे। हैली, न्यूटन के समकालीन थे। उन्होंने धूमकेतुओं के बारे में अध्ययन किया था।एडमंड हैली का जन्म 8 नवम्बर, 1656 को शोरडिच, इंग्लैंड में हुआ था। यह एक प्रसिद्घ खगोलशास्त्री थे। हैली, न्यूटन के समकालीन थे। उनके पिता का साबुन का कारोबार था। बचपन से ही हेली की गणित में खास रुचि थी। ऑक्सफोर्ड यूनिवर्सिटी के क्वींस कॉलेज से स्नातक की पढ़ाई के दौरान भी उन्होंने सौरमंडल और सौर बिंदुओं के बारे लिखा। 1675 में वह ग्रीनविच ऑब्सरवेटरी में खगोलशास्त्री जॉन फ्लैमस्टीड के सहायक के रूप में काम करने लगे। 22 साल की उम्र में हेली ने ऑक्सफोर्ड से मास्टर की डिग्री हासिल की और रॉयल सोसाइटी में फेलो रिसर्चर के तौर पर चुने गए।

हैली ने धूमकेतुओं के बारे में अध्ययन किया। उनका कहना था कि जो धूमकेतु सन 1682, में दिखायी दिया था यह वही धूमकेतु है जो सन् 1531 व 1607 तथा संभवत: सन 1465 में भी दिखायी पड़ा था। उन्होंने गणना द्वारा भविष्यवाणी की कि यह सन 1758 के अन्त के समय पुन: दिखायी पड़ेगा। ऎसा हुआ भी कि यह पुच्छल तारा 1758 के बड़े दिन की रात्रि को दिखलायी दिया। तब से इसका नाम हैली का धूमकेतु पड़ गया।

हैली की मृत्यु 14 जनवरी 1742 को हो गयी यानि उन्होंने अपनी भविष्यवाणी सच होते नहीं देखी। इसके बाद यह पुच्छल तारा नवम्बर 1835, अप्रैल 1910, और फ़रवरी 1986 में दिखायी पड़ा।

Edmond Halley, FRS ( 8  Nov 1656 – 14 January 1742) was an English astronomer, geophysicist, mathematician, meteorologist, and physicist who is best known for computing the orbit of Halley's Comet. He was the second Astronomer Royal in Britain, succeeding John Flamsteed.Halley was born in Haggerston, in east London. His father, Edmond Halley Sr., came from a Derbyshire family and was a wealthy soap-maker in London. As a child, Halley was very interested in mathematics. He studied at St Paul's School, and from 1673 at The Queen's College, Oxford. While still an undergraduate, Halley published papers on the Solar System and sunspots.While at Oxford University, Halley was introduced to John Flamsteed, the Astronomer Royal. Influenced by Flamsteed's project to compile a catalog of northern stars, Halley proposed to do the same for the Southern Hemisphere.

In 1676, Halley visited the south Atlantic island of Saint Helena and set up an observatory with a large sextant with telescopic sights to catalogue the stars of the southern hemisphere.While there he observed a transit of Mercury, and realised that a similar transit of Venus could be used to determine the absolute size of the Solar System.He returned to England in May 1678. In the following year he went to Danzig (Gdańsk) on behalf of the Royal Society to help resolve a dispute. Because astronomer Johannes Hevelius did not use a telescope, his observations had been questioned by Robert Hooke. Halley stayed with Hevelius and he observed and verified the quality of Hevelius' observations. In 1679, Halley published the results from his observations on St. Helena as Catalogus Stellarum Australium which included details of 341 southern stars.These additions to contemporary star maps earned him comparison with Tycho Brahe: e.g. "the southern Tycho" as described by Flamsteed. Halley was awarded his M.A. degree at Oxford and elected as a Fellow of the Royal Society at the age of 22. In September 1682 he carried out a series of observations of what became known as Halley's Comet, though his name became associated with it because of his work on its orbit and predicting its return in 1758 (which he did not live to see).

In 1686, Halley published the second part of the results from his Helenian expedition, being a paper and chart on trade winds and monsoons. The symbols he used to represent trailing winds still exist in most modern day weather chart representations. In this article he identified solar heating as the cause of atmospheric motions. He also established the relationship between barometric pressure and height above sea level. His charts were an important contribution to the emerging field of information visualisation.

Halley 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, much as John Flamsteed had done four years earlier, only to find that Newton had solved the problem, at the instigation of Flamsteed with regard to the orbit of comet Kirch, without publishing the solution. Halley asked to see the calculations and was told by Newton that he could not find them, but promised to redo them and send them on later, which he eventually did, in a short treatise entitled, On the motion of bodies in an orbit.

Halley recognised the importance of the work and returned to Cambridge to arrange its publication with Newton, who instead went on to expand it into his Philosophiæ Naturalis Principia Mathematica published at Halley's expense in 1687. Halley's first calculations with comets were thereby for the orbit of comet Kirch, based on Flamsteed's observations in 1680-1. Although he was to accurately calculate the orbit of the comet of 1682, he was inaccurate in his calculations of the orbit of comet Kirch. They indicated a periodicity of 575 years, thus appearing in the years 531 and 1106, and presumably heralding the death of Julius Caesar in a like fashion in −44 (45 BCE). It is now known to have an orbital period of circa 10,000 years.

In 1691, Halley built a diving bell, a device in which the atmosphere was replenished by way of weighted barrels of air sent down from the surface. In a demonstration, Halley and five companions dived to 60 feet (18 m) in the River Thames, and remained there for over an hour and a half. Halley's bell was of little use for practical salvage work, as it was very heavy, but he made improvements to it over time, later extending his underwater exposure time to over 4 hours. Halley suffered one of the earliest recorded cases of middle ear barotrauma.  That same year, at a meeting of the Royal Society, Halley introduced a rudimentary working model of a magnetic compass using a liquid-filled housing to damp the swing and wobble of the magnetised needle.

In 1691, Halley sought the post of Savilian Professor of Astronomy at Oxford. While a candidate for the position, Halley faced the animosity of the Astronomer Royal, John Flamsteed, and his religious views were questioned. His candidacy was opposed by both the Archbishop of Canterbury, John Tillotson, and Bishop Stillingfleet, and the post went instead to David Gregory, who had the support of Isaac Newton.

In 1692, Halley put forth the idea of a hollow Earth consisting of a shell about 500 miles (800 km) thick, two inner concentric shells and an innermost core. He suggested that atmospheres separated these shells, and that each shell had its own magnetic poles, with each sphere rotating at a different speed. Halley proposed this scheme to explain anomalous compass readings. He envisaged each inner region as having an atmosphere and being luminous (and possibly inhabited), and speculated that escaping gas caused the Aurora Borealis.

In 1693 Halley published an article on life annuities, which featured an analysis of age-at-death on the basis of the Breslau statistics Caspar Neumann had been able to provide. This article 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.

The Royal Society censured Halley for suggesting in 1694 that the story of Noah's flood might be an account of a cometary impact. However, he was to be vindicated less than three centuries later after the publication of "Und die Sintflut gab es doch" by professors Alexander & Edith Tollmann of the University of Vienna. Their book presents evidence from the geologic record that a comet had split up and then struck the earth in Shoemaker-Levy fashion about 10 millennia ago.

Halley married Mary Tooke in 1682 and settled in Islington. The couple had three children.