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Edmund Halley
November 8, 1656 – January 14, 1742
 


The English astronomer Edmund Halley studied the orbital movements of the moon and of comets and discovered the proper motion of the fixed stars.
 

 

The son of a prosperous London soap-boiler, Edmund Halley was born on Nov. 8, 1656, in Haggerston near London. He attended St. Paul's School, where he excelled in classics and mathematics and early developed an interest in astronomy. At the age of 16, when he entered Queen's College, Oxford, he was already an accomplished astronomical observer. He continued his observations at Oxford and, before he was 20, had sent to the Royal Society an explanation of an improved means of calculating planetary orbits.

Recognizing the need for more accurate star charts, Halley, while still an undergraduate, proposed a plan for surveying the stars of the southern hemisphere as a supplement to the surveys then being made of the northern hemisphere by John Flamsteed and Johannes Hevelius. He left Oxford without a degree and in 1676 journeyed to the island of St. Helena in the South Atlantic. St. Helena's frequent cloud cover made it poorly suited for astronomical observations, although in 18 months on the island Halley managed to determine the position of approximately 350 stars. In addition, he made one of the first complete observations of a transit of Mercury; it occurred to him that similar transits might be used to accurately calculate the sun's distance from the earth. He returned to England in 1678, published his results, and was dubbed by Flamsteed "the Southern Tycho, " a reference to the famous Danish astronomer Tycho Brahe.


Publication of Newton's "Principia"

Upon his return Halley received, by royal mandate, his Oxford degree and, at the age of 22, was elected a fellow of the Royal Society. After 2 years of travelling on the Continent, he returned to London, where he married and, in 1682, began a lengthy series of lunar observations. Designed to last for 18 years, these observations were to correct tables of the moon's position in an effort to solve the problem of accurately determining longitude. Such a lengthy project was not, however, well suited to Halley's temperament, and he was soon diverted to other concerns.

Intensely interested in the problem of gravitation, Halley had obtained by 1684 an inverse-square relationship, but since he was unable to deduce from it the planetary motions, in August that year he travelled to Cambridge to seek the assistance of Newton. What would be the orbit of a planetary body subjected to such a force? An ellipse, Newton replied. He had earlier proved that this was so and shortly thereafter sent Halley a copy of his demonstration. Realizing the significance of what Newton had done, Halley, utilizing great skill and tact, persuaded the reluctant Newton to develop and publish his ideas on celestial mechanics. Newton's Principia was published in 1687. Halley read the manuscript, corrected the proofs, and paid the publication costs out of his own pocket. A lasting friendship ensued, and in 1696, through Newton's influence, Halley was appointed deputy comptroller of the Mint at Chester.


Astronomical and Physical Observations

Halley maintained a lifelong interest in the declination of the magnetic compass, and he published two significant papers (1683 and 1692) discussing the causes of this variation and its change with time. Between 1698 and 1702 he undertook a series of government-sponsored expeditions to make extensive measurements of terrestrial magnetism in the South Atlantic and to study in detail the tides and coast of the English Channel. He correlated the data from his South Atlantic voyages with other measurements he had been collecting and in 1702 published for the first time a map showing lines of equal declination. Of great navigational value, these lines (known today as isogonics) were for years called "Halleyan lines."

Halley's calculation of the periodic nature of comets was perhaps his most significant contribution to astronomy. In his Synopsis of the Astronomy of Comets (1705) he collected and analyzed all known observations of comets and computed the parabolic orbits of 24 comets dating from 1337 to 1698. The orbital elements of three (1531, 1607, and 1682) were so similar as to suggest that they were in fact the successive returns of a single body whose orbit was an enormous elongated ellipse, rather than a parabola, and whose period of revolution was approximately 76 years. Halley successfully predicted the return of this comet in 1758 and suggested that other comets might also have elliptical orbits. Halley's comet, as it is known today, returned on schedule in 1835, 1910, and 1986.

Before Halley's discovery of the "proper motion" of fixed stars, it was believed that they (unlike the planets) never moved in relation to each other. In 1718, however, Halley pointed out that three of the brightest stars (Sirius, Procyon, and Arcturus) had apparently changed their relative positions markedly since having been observed by the Greeks. In fact, Sirius appeared to have moved perceptibly since observed by Tycho Brahe only a century and a half earlier. After carefully comparing the positions of other stars and establishing that this apparent movement could not be accounted for by any motion of the earth, Halley concluded that the three had actually shifted their relative positions and suggested that, if observed over sufficiently long periods, this proper motion might also be detected in other stars as well.

Halley's knowledge and interests were extensive. He pursued such varied topics as the magnetic origin of the aurora borealis, the design and construction of diving bells, and the establishment of quantitatively accurate mortality tables. He continued his astronomical observations until a few months before his death on Jan. 14, 1742.
 


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Edmond Halley FRS (November 8, 1656 – January 14, 1742) was an English astronomer, geophysicist, mathematician, meteorologist, and physicist.


Biography and career

Halley was born in Haggerston, Shoreditch, England, the son of a wealthy soapboiler. As a child, Halley was very interested in mathematics. He studied at St Paul's School, and then, from 1673, at The Queen's College, Oxford. While an undergraduate, Halley published papers on the solar system and sunspots.

On leaving Oxford, in 1676, Halley 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 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. The same year, Halley published Catalogus Stellarum Australium which included details of 341 southern stars. These additions to present-day star maps earned him comparison with Tycho Brahe. Halley was awarded his M.A. degree at Oxford and elected as a Fellow of the Royal Society.

In 1686 Halley published the second part of the results from his St. Helena 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 barometric pressure and height above sea level. His charts were an important contribution to the emerging field of information visualization.

Halley married Mary Tooke in 1682 and settled in Islington and the couple had three children. 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 Sir 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 1690, 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 did make improvements to it over time, later extending his underwater exposure time to over 4 hours. 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 magnetized needle.

In 1691 Halley sought the post of Savilian Professor of Astronomy at Oxford, but, due to his well-known atheism, was opposed by the Archbishop of Canterbury, John Tillotson and Bishop Stillingfleet. The post went instead to David Gregory, who had the support of Isaac Newton.

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.

In 1698, Halley was given the command of the 52 foot (16 m) pink, Paramour (a pink was a form of small unrated vessel, akin to a sloop), so that he could carry out investigations in the South Atlantic into the laws governing the variation of the compass. On 19 August 1698, he took command of the vessel and, in November 1698, sailed on what was the first purely scientific voyage by an English naval vessel. Unfortunately problems of insubordination arose, allegedly by officers resentful of being under a civilian's command. The Paramour returned to England in July 1699. Halley thereupon received a commission as a temporary Captain in the Royal Navy, recommissioned the Paramour on 24 August 1699 and sailed again in September 1699 to make extensive observations on the conditions of terrestrial magnetism. This task he accomplished in a second Atlantic voyage which lasted until 6 September 1700, and extended from 52 degrees north to 52 degrees south. The results were published in General Chart of the Variation of the Compass (1701). This was the first such chart to be published and the first on which isogonic, or Halleyan, lines appeared.

In November 1703 Halley was appointed Savilian Professor of Geometry at Oxford University, his theological enemies, John Tillotson and Bishop Stillingfleet having passed away, and received an honorary degree of doctor of laws in 1710. In 1705, applying historical astronomy methods, 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 doing so he was following the method described by James Gregory in Optica Promota (in which the design of the Gregorian telescope is also described). It is reasonable to assume Halley possessed and had read this book given that the Gregorian design was the principal telescope design used in astronomy in Halley's day. It is not to Halley's credit that he failed to acknowledge Gregory's priority in this matter. In 1718 he discovered the proper motion of the "fixed" stars by comparing his astrometric measurements with those given in Ptolemy's Almagest. Arcturus and Sirius were two noted to have moved significantly, the latter having progressed 30 arc minutes (about the diameter of the moon) southwards in 1800 years.


Grave of Edmond Halley

In 1720, together with his friend the antiquarian William Stukeley, Halley participated in the first attempt to scientifically date Stonehenge. Assuming that the monument had been laid out by the use of a magnetic compass, Stukeley and Halley attempted to calculate the perceived deviation introducing corrections from existing magnetic records, and suggested three dates (AD 920, AD 220 and 460 BC), the earliest being the one accepted. These dates were wrong by thousands of years, but the idea that scientific methods could be used to date ancient monuments was revolutionary in its day.

Halley succeeded John Flamsteed in 1720 as Astronomer Royal, a position Halley held until his death in Greenwich at the age of 85. Halley was buried in the graveyard of the old church of St. Margaret, Lee (now ruined). In the same vault is Astronomer Royal John Pond; the unmarked grave of Astronomer Royal Nathaniel Bliss is nearby.


Hollow Earth

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, about the diameters of the planets Venus, Mars, and Mercury. 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 in order 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.


Named after Halley

Plaque in South Cloister of Westminster Abbey

* Halley's Comet — Halley predicted the comet's return.
* Halley crater on Mars.
* Halley crater on the Moon.
* Halley Research Station, Antarctica.
* Halley's method, for the numerical solution of equations.
* Halley Street, in Blackburn, Victoria, Australia.
 


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Edmond Halley was born in Hagerston, Middlesex, England (near London) as son of a wealthy merchant, salter and soapmaker. His birth date is somewhat uncertain because it is not known if at that time in his village the Gregorian or the Julian calendar was in use. There's also some dispute over the year.

He got educated at Oxford and studied at Oxford University, Queen's College, 1673-6. He worked with John Flamsteed, the Astronomer Royal in 1675-6 both at Oxford and Greenwich, and observed e.g. the occultation of Mars by the Moon on August 21, 1676.

In November 1676, he gave up his studies without final exam, and sailed to St. Helena on the southern hemisphere, in order to compile a catalog of southern stars. The reasons for this are unknown, but it may be that he wanted to complement Flamsteed's mapping of the northern celestial hemisphere on the southern skies. Besides compiling this first catalog of the southern skies, Halley observed the Mercury transit of November 7, 1677. After returning to England in 1678, he got his "Catalog of the Southern Stars" published (Halley 1679).

On his return, Halley was elected to the Royal Society on November 30, 1678, and King Charles II graduated him by mandate in 1679. That year, he was sent to Danzig to visit Hevelius.

In the years following, he travelled Europe, urged Isaac Newton to work out and publish his Principia, and acquired the expressed enemyship of John Flamsteed. In 1691 Flamsteed succeeded in preventing his appointment as professor in Oxford. In 1704 he was eventually appointed Savilian professor of geometry at Oxford, well to the dismay of Flamsteed.

Halley had observed a number of comets and, following 1695, undertook deep studies to calculate their orbits. In 1705, he published his "Astronomiae Cometiae Synopsis", including his observation that the comet he had observed in 1682 had an orbit almost identical to those of the comets of 1531 and 1607, and concluded these were apparitions of one and the same comet, the return of which he predicted for 1758.

In 1710, Halley discovered the proper motion of some "fixed" stars when using Ptolemy's catalog. In 1712, he arranged to publish Flamsteed's observations and star catalogs, an endeavor he had worked on for a long time, heavily opposed by Flamsteed - who later (in 1715) arranged to burn all remaining copies he could get, about 300 of the total edition of 400. In 1715, Halley published a summary of the variable ("New") stars known at that time, six in number (Halley 1715), and in 1716, a summary on the known "nebulae", also six (Halley 1716).

When Flamsteed died, his favorite enemy Halley succeeded him in 1720, then at age 64, and held this position for 21 years.

Halley passed away on January 14, 1742 in Greenwich, England at age 87.

The astronomical community has honoured Halley by naming each one crater on Moon (8.0S, 5.7E, 36.0 km diameter, named in 1935) and Mars (48.7S, 59.3W, 84.5 km, in 1973) after him. Asteroid No. 2688 was named Halley, on its discovery by E. Bowell at Anderson Mesa on April 25, 1982; previously it had been cataloged as 1982 HG1 and former pre-discovery sightings as 1955 QN1 = 1978 SH6 = 1978 TE9 = 1978 UO. But certainly he is best remembered for the comet which he first predicted to return, the most famous of all comets, Comet 1P/Halley.

Halley originally discovered two deepsky objects, globular clusters Omega Centauri (NGC 5139) and the Hercules Cluster, M13. His "Catalog of Southern Stars" (Halley 1679) includes 3 nebulous objects, and he wrote one of the first papers on nebulae, including a catalog of 6 entries/objects (Halley 1716).


 

 

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