• Born: 8 November 1656
• Birthplace: Haggerston, England
• Died: 14 January 1742 (natural causes)
• Best Known As: Discoverer of Halley's Comet

Edmond Halley was the first man to recognize the recurring astronomical visitor now known as Halley's Comet. Halley was already interested in the stars when he entered Queen's College, Oxford at the age of 16. He later left Oxford without a degree and became a protege of the Astronomer Royal, John Flamsteed. Halley and Flamsteed had a falling out, but by age 22 Halley had already been elected to the prestigious Royal Society. In 1705 he published Synopsis on Cometary Astronomy, in which he argued that prominent comets observed in 1531, 1607 and 1682 had all been the same comet, returning to pass Earth on a cycle of about 76 years. He was proven correct when the comet returned on Christmas Day of 1758 (though Halley himself had died in 1742), and the comet has since been known as Halley's Comet. Halley became a professor at Oxford in 1704 and succeeded Flamsteed as Astronomer Royal in 1720. Multitalented and exceedingly brainy, Halley also contributed to other scientific fields during his long career; he is especially known for inventing the diving bell.

In scientific circles, Halley's Comet is more properly known as Comet Halley... Halley was a friend and staunch supporter of Sir Isaac Newton; he paid for the initial printing of Newton's Principia Mathematica... Halley's name is sometimes spelled Edmund... Halley's Comet last passed Earth in 1986, and is due to return in 2061... Writer Mark Twain was born and died in Halley's Comet years: 1835 and 1910... Halley inspired the punning name of the rock band Bill Haley and the Comets, which recorded "Rock Around the Clock" in 1954.

Edmond Halley

Library of Congress

[b. Haggerston, England, November 8, 1656, d. Greenwich, England, January 14, 1742]

Halley's contributions to science began as an astronomer, starting in 1676 when he traveled to Saint Helena to catalog the then unmapped stars of the Southern Hemisphere. In 1705 Halley wrote that comets travel in orbits that periodically bring them back to Earth's vicinity and correctly proposed that the comet of 1682 would return in 1758. In 1710, after comparing current positions of stars with those listed in Claudius Ptolemy's star catalog, Halley was the first astronomer to recognize that stars have motions of their own and that the Moon gradually changes its orbit.

Halley also studied Earth's magnetic field and weather, explaining the cause of monsoon winds and the relation between weather and barometric pressure. He invented the diving bell. Perhaps his greatest contribution to science, however, was persuading Newton to write the Principia.

The English astronomer Edmund Halley (1656-1742) 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 traveling 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 traveled 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.

Further Reading

Selections from Halley's correspondence and unpublished papers, together with two 18th-century biographical memoirs, are in Eugene Fairfield MacPike, ed., Correspondence and Papers of Edmund Halley (1932). The best biography of Halley is Angus Armitage, Edmund Halley (1966). Also useful is Colin A. Ronan, Edmund Halley:Genius in Eclipse (1969). For Halley's relations with contemporary astronomers see Eugene Fairfield MacPike, Hevelius, Flamsteed and Halley (1937).

Additional Sources

Standing on the shoulders of giants:a longer view of Newton and Halley, Berkeley:University of California Press, 1990.

For more information on Edmond Halley, visit Britannica.com.

Halley, Edmond (1656-1742). Astronomer, remembered because his name is attached to a comet. Leaving Queen's College, Oxford, without a degree in 1676, he went to St Helena to map the southern stars. After a famous meeting with Wren and Hooke, he visited Newton in Cambridge, and hearing about his work on gravitation, persuaded him to publish it. In 1703 he became professor of astronomy at Oxford, and in 1720 astronomer-royal. He computed the orbits of several comets, and deduced that those of 1456, 1531, 1607, and 1682 were periodic returns of the same body.

(hăl'ē, hô'lē) , 1656–1742, English astronomer and mathematician. He is particularly noted as the first astronomer to predict the return of a comet and the first to point out the use of a transit of Venus in determining the parallax of the sun. In 1676 he went to St. Helena to observe the southern skies and as a result made a catalog of 341 stars of the Southern Hemisphere. In 1677 he made the first complete observation of a transit of Mercury. He financed the publication of Isaac Newton's Principia and helped to prepare it for the press. On the basis of Newton's theory, Halley calculated the orbit of the great comet of 1682—since known as Halley's comet—and predicted its return in 1758. In 1698–1700 he made one of the first studies of compass variations in the North Atlantic. He was made astronomer royal in 1720. He observed the moon through the complete revolution of its nodes; this took 18 years. Other discoveries of Halley's are the proper motions of the stars and the acceleration of the moon's mean motion. His noted synopsis of known comets appeared in 1705; his Tabulae astronomicae (1749, tr. 1752) was published posthumously.

Bibliography

See his Correspondence and Papers (repr. 1975); biography by C. A. Ronan (1970); L. Baldwin, Edmond Halley and His Comet (1985).

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