George Biddell Airy

Sir George Biddell Airy ( born July 27, 1801 in Alnwick, Northumberland, † January 2, 1892 in Greenwich ) was an English mathematician and astronomer. He made ​​significant contributions to celestial mechanics, astrometry and optics.

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Life and work

Training

Airy comes from a family whose ancestors lived in Westmorland in the 14th century. The members of the branch, who belonged Airy, had to move to Lincolnshire and operate in the aftermath agriculture due to the English Civil War.

Airy attended primary school in Hereford and then the " Royal Grammar School " in Colchester. A wealthy relative furthered his academic training and his enthusiasm for physics.

From 1819 he studied at Trinity College, University of Cambridge. Due to excellent performance, he was repeatedly Best Years. In 1823 he completed his studies and was awarded the " Smith Prize ". The following year he entered Cambridge to the post of lecturer in mathematics. In December 1826, he took over as successor to Thomas Turton to Luca -sian chair of mathematics. However, he had held for only a little more than a year the chair because he was "Experimental Philosophy " appointed in February 1828 as professor of astronomy and and head of the newly established Cambridge Observatory took over.

Astronomer in Cambridge

At this time the only telescope of the observatory was a " transit instrument " for the determination of star positions. Airy thus resulted from careful measurements, which he published annually. 1833 quadrant was purchased and the Duke of Northumberland bequeathed to the observatory a high quality telescope with 30 cm aperture. The device was placed on a constructed of Airy Mount.

During his time in Cambridge itself Airy dealt with mathematical, physical and astronomical problems. His publications include essays on the refraction of light by lens glasses ( the so-called Airy disk are still used to assess the quality of telescopes ), the formation of rainbows and discovered the astigmatism of the human eye. He calculated the mass of the planet Jupiter and examined the perturbations of Earth and Venus. The latter work was very important and led to the improvement of astronomical tables. The Royal Astronomical Society awarded him for 1833 with their gold medal.

In addition, he presented a comparison of the progress in astronomy in England and other countries, which turned out very unfavorable for England.

His time in Greenwich

In June 1835 Airy was appointed as the successor of John Pond to the Astronomer Royal and director of the Royal Greenwich Observatory. The working conditions at the observatory were inadequate according to Airy's opinion, so he organized the entire operation again. He revised the existing records, set the foundation of a library sure left a equatorial telescope by Richard Sheepshanks up and set up an observatory to measure the Earth's magnetic field.

1847 Airy had set up a telescope with equatorial mount, which allowed a better observation of the moon; until then the moon in Greenwich could only be observed when passing through the meridian. In 1848 he invented a diagonal prism for easier observations of stars in the zenith. 1850 Meridian telescope with 20.3 cm aperture and 3.5 m focal length was put into operation in 1859 was followed by a telescope with 33 cm aperture. From 1868 they worked in Greenwich in the field of spectroscopy and of 1873 of photographs of sunspots could be made.

Airy sighted the extensive data of the lunar observations made at Greenwich from 1750 to 1830. Arose a summary of 8,000 observations that had been made under his predecessors James Bradley, Nathaniel Bliss, Nevil Maskelyne and John Pond. The data were astronomers from 1846 are available and could for comparison purposes and the improvement of astronomical tables are used. The Danish astronomer Peter Andreas Hansen presented at the observatory Gotha from the data two more irregularities in the orbit of the moon around the earth firmly. By Airy's influence Hansen received financial support from the British Admiralty and was his famous Tables de la Lune (Moon signs) finish. Lunar tables were for the naval power of England great importance because with their help, the tide could be accurately determined. For his work Airy was awarded in 1848 for the second time with the Gold Medal of the Royal Astronomical Society.

Another object of research Airy was to determine the mean density of the planet Earth. He tackled the problem by means of commuting, he was swinging at the surface and at depth. In 1826 he began experiments in " Dolcoath Mine" in Cornwall, where the underground established pendulum, however, was spilled. Another experiment had to be discontinued because of flooding. Airy was able to continue his studies until much later. Another experiment took place probably in 1854 " Harton Pit ", near South Shields. Airy was clear from the different vibrational frequencies that gravity is greater at a depth of 383 m, than at the surface. For the density of the earth, he headed a value of 6.566 g/cm3 from (the actual value is 5.515 g/cm3), also goes back to him a model of isostasy.

1872 Airy devised a method for exact numerical determination of the moon's orbit, which he published in the news of the Royal Astronomical Society. It was based on Charles -Eugène Delaunay numeric expressions to the provisions of the latitude, longitude and parallax, which terms were inserted into the system of equations. The orbit determination required an immense computational work and Airy published the results in 1886, at the age of 85 years. Shortly before the suspect had come to him that his calculations had errors, for a complete overhaul but it lacked the forces due to age. In 1890, he shared with resignation, that a serious error had crept in the first steps of calculation.

By Airy's activities became the Royal Greenwich Observatory global validity. From 1872 to 1873 was president of the Royal Astronomical Society Airy. Since 1840 he was a member of the Bavarian Academy of Sciences. In 1881 he resigned from all official posts. He lived until his death in 1892 in the "White House " in the vicinity of the observatory.

Honors

1833 and again in 1846 he was awarded a Gold Medal of the Royal Astronomical Society. 1836 Airy was elected as a member ( "Fellow" ) to the Royal Society, of which he received the 1831 and 1845 Copleymedaille Royal Medal. In addition, he was taken on January 24, 1854 in the Prussian Order Pour le Mérite for Arts and Science as a foreign member.

Terms

After Airy were named among other things:

• The Airy functions and in mathematics.
• The lunar crater Airy.
• The Mars crater Airy, and therein, the prime meridian defining smaller martian crater Airy -0.
• Are the Airy disk in optics and astronomy called the Airy disk. These are the smaller the greater the aperture of the telescope.
• The Airy formula for wavelength electromagnetic radiation.
• Airy stress function in the theory of elasticity