Edmond Halley

Edmond Halley (born 29 Oktoberjul / November 8 1656greg in Haggerston in London, .. .. † January 14 1741jul / January 25 1742greg in Greenwich ) was an English astronomer, mathematician, cartographer, geophysicist and meteorologist.

Life

Halley studied mathematics and astronomy at Oxford and was able to publish the age of 21 a method to determine the aphelia and eccentricities of the planets. He traveled in 1677 to St. Helena. He was able to observe a transit of Mercury from the beginning to the end of the first astronomer on November 7, 1677. He then proposed to measure Mercury and Venus transits for determining the astronomical unit to determine the size of the solar system. This proposal had already been made before James Gregory in his book Optica Promota, Halley was most likely known. He also surveyed there the positions of 341 stars of the southern sky. In 1686 he published the observations of the Passat and monsoon winds that he had collected on this trip. Commissioned by the Royal Society, whose secretary he was later, Halley traveled to Gdansk, to settle the scientific dispute between Robert Hooke and Johannes Hevelius.

In the years 1680 to 1681 Halley traveled to France and Italy and initiated the scientific collaboration between the Observatories of Greenwich and Paris. Between Calais and Paris Halley first observed the comet later named after him. From 1677 he always had by his calculations to the importance of Venus passages for the determination of the solar parallax.

In 1684 he discussed in a London coffee house with Christopher Wren and Robert Hooke evidence of Kepler's laws. And there was found no solution, it was decided to turn to Isaac Newton. In August 1684 Halley visited Newton in Cambridge, who had to solve the problem in the drawer. Halley convinced him to complete the work. He reached also the printing costs for the Principia. This brought him into serious financial difficulties, especially as the Royal Society not only contributed nothing but his salary as her secretary paid off not in cash but in the form of books ( De Historia Piscium ).

Between 1698 and 1700 Halley traveled as commander of the warship HMS Paramore the South and North Atlantic, to determine the direction of the magnetic needle at different points of the earth's surface. As a result of these trips in 1701 he was able to publish the first major card of the magnetic declination. In further travels he surveyed the English Channel and visited the Adriatic ports.

1703 convened the University of Oxford Halley on the Savilischen Chair of geometry. There he worked on the theory of the moon in order to improve it to the application to length rules for the lake. In 1705 he was able to calculate the orbital elements of comets ( the 1531, 1607 and 1682) according to this new method. By these calculations, the suspicion arose that these were symptoms always the same comet, which will return to the beginning of 1759. Since the prediction confirmed, this comet has since been known as Halley 's Comet.

When in 1719 the Astronomer Royal ( Astronomer Royal) John Flamsteed died, was yet to be appointed in the same year Halley as his successor in Greenwich. With effect of taking office in Greenwich Halley gave up his spot on as secretary of the Academy of Sciences. As an astronomer at Greenwich he revised the rating list of Ptolemy and published it in Geographiae veteris Scriptores minores Graeci.

Work

In addition to his calculations of orbits of comets (eg Halley 's Comet ) explored Halley also terrestrial magnetism and the monsoon, and discovered the proper motion of stars.

But he also went up to improve the diving bell deserves. In 1690 he appeared with five colleagues for one and a half hours in the Thames 20 m deep. He combined this with bell complained and anchored below the bell drums with air, so that they could flow upward. Later he improved the system to the extent that he could stay under water for four hours.

He also improved the Spiegeloktanten, an instrument for astronomical observations ( for navigation) on the sea. As a mathematical advisor to the Amicable and Perpetual Assurance Halley created the mathematical foundations of life insurance mathematics.

Halley but also dealt with questions of chronology of classical antiquity. In his essay on inscriptions in Palmyra, however, no astronomical observations to determine the slowing down of the Earth's rotation are treated contrary to almost all related sites. Halley says in the last paragraph only that one must find old inscriptions to determine the secular acceleration of the moon (which by the Earth's rotation slowed seemingly accelerated motion of the Moon ).

Halley also translated classical mathematical treatises such as the conic teaching of Apollonius of Perga from Arabic.

The solution to the length problem occupied him throughout his life. On this background, you have to see his mapping of the geomagnetic field and its below -mentioned theory of the hollow earth. He also supported the proposal made ​​in 1714 by William Whiston and Humphry Ditton, the British Parliament to launch an high cash prize for solving the problem.

Hollow earth

In 1691, he proposed the first hollow earth theory before on a scientific basis. Isaac Newton had calculated that the moon is denser than the Earth. Starting from the general view, all matter of the planets and moons would have the same density, Halley concluded that part of the earth must be hollow. In addition, he had observed that the magnetic field of the earth has four poles and changes with time. He assumed that the Earth consists of a central ball and concentrically surrounding three hollow balls, about the size of the planet Moon, Mercury, Venus. Each of these bodies has its own magnetic field, and since they rotate at different speeds, results on the surface of the earth a changing total magnetic field. Since at that time assumed that all celestial bodies are inhabited, he populated the inner planets. These hollow earth theory is the first conclusion from the new theory of gravitation Newton in the Principia, before Halley's prediction of a comet of 1695th very bright auroras were on 6 March 1716 in the UK and most of Europe for the first time after the Maunder Minimum again observed, even at days visible. The Royal Society commissioned Halley to explain these phenomena. He led her back to the fact that the earth's crust in northern latitudes is characterized by thin and seem the light from the cavities. When the 80 -year-old Halley was portrayed as Astronomer Royal, he allowed himself to depict with a diagram of the hollow earth.

Aftereffect

From 21 to November 22, 1956 an exhibition was held in the rooms of the Royal Society on the occasion instead of Halley's 300th birthday. Portions of this exhibition were subsequently shown from 31 December 1956 to 20 January 1957 at the British Museum.

After Edmond Halley, the asteroid ( 2688 ) Halley, the comet 1P/Halley, the moon crater Halley, the Mars crater Halley and the Halley station in Antarctica and the Halley method designated to zeros determination.

Writings (selection )

• Methodus Directa & Geometrica, decedent Ope Investigantur Aphelia, Eccentricitates, Proportionesque Orbium Planetarum Primariorum, Absque Supposita Aequalitate Anguli motus ad Alterum Ellipsews focum, from Astronomis Hactenus Usurpati. In: Philosophical Transactions. Volume 11, London 1676, pp. 683-686, DOI: 10.1098/rstl.1676.0031.
• Catalogus Stellarum Australium sive Supplementum Catalogi Tychonici. London 1679 (online).
• An Account of the Cause of the Change of the Variation of the Needle Magnetical; With an Hypothesis of the Structure of the Internal Parts of the Earth: As It Was Proposed to the Royal Society in One of Their Late meetings. In: Philosophical Transactions. Volume 16, London 1692, pp. 563-578, DOI: 10.1098/rstl.1686.0107.
• Some Account of the Ancient State of the City of Palmyra, with Short Remarks upon the Inscriptions Found there. In: Philosophical Transactions. Volume 19, London 1695, pp. 160-175, DOI: 10.1098/rstl.1695.0023.
• A new and correct sea chart of the whole world shewing the variations of the compass as theywere found in the year MDCC. Mount & Page, London 1702 (online).
• Astronomiae Cometicae Synopsis. In: Philosophical Transactions. Volume 24, London 1705, pp. 1882-1899, DOI: 10.1098/rstl.1704.0064. A Synopsis of the Astronomy of the Comets. In: Miscellanea Curiosa: Being a Collection of some of the Principal Phenomena in Nature. Volume 2, London 1706, pp. 321-344 (online).

• Edmundi Halleii Astronomy dum Viveret Regii tabulae astronomicae accedunt de usu Tabularum praecepta. J. Brevis, London, in 1749.