Abul-Abbas Ahmad ibn Muhammad ibn Kasir al Farghani
Astronomer, mathematician, and engineer
The exact date of birth and death of Ahmad al Farghani is not known. It is obvious from his name that he is from Ferghana. In Western Europe he was recognized of Latin name - Alfraganus.
Ahmad al Farghani worked together with Muhammad al Khorazmi in Bayt al Hikma (The House of Wisdom) in Bagdad. He participated in measuring the length of a meridian degree in Sanjar desert in Iraq.
The only reliable date in the biography of Ahmad al-Fargani is 861, when he built a new Nilometer (scale that measures water level of the Nile) on the island of Rauda near Cairo, which functioned until 1971, i.e. until the Aswan Dam construction.
The Main Scientific Works
The list of preserved to date, 11 works by Ahmad al Farghoni written in the Arabic language includes – Kitab fi usul ilm an-nujum («The elements of astronomy»), Bab fi ma’rifa al-vaqt al-lati yakuni al-kamar fiha fa-vqa al-ard av tahtakha («the Treatise on time, when the Moon goes under and above the Earth»), Hisab al-akalim as-sab’a («The calculus of seven climates»), al-Kamil fi san’a al-asturlab ash-shimali wa-l-janubi bi-l handasa wa-l-hisab («A comprehensive book on the structure of the north and south astrolabe supplied with geometrical justification»), Kitab amal ar-ruhamat («A book of construction of sundials»), Kitab amal bi-l asturlab («A book of operations with astrolabe») and many others.
The “Elements of Astronomy” used as a textbook for astronomy classes, was translated in the XII century into the Latin language and was very popular in Europe. The book contains evidence for spherical form of the Earth and the data on the planet’s size, which induced Ch. Columbus, F. Magellan and other travelers to make geographical discoveries.
Both «A comprehensive book on structure of the north and south astrolabe supplied with geometrical justification», and «A book of construction of sundials», contain guidelines for designing, making and applying astronomic tools – astrolabes (a planar astronomic instrument made of copper, bronze or other similar alloys, which is used for defining the coordinates of celestial bodies) and sundials.
In his “Book of operations with astrolabe” Ahmad al-Farghoni, proved the theorem of Ptolemy on the stereographic projection (stereographic projection – projecting of points on the surface of the imaginary heavenly sphere from one pole on to the plane crossing through its other pole, or on to the plane containing the equator), which is recognized as the main theory of astrolabe – the most popular medieval astronomic instrument.
Contribution to the World Science
The book “Elements of Astronomy” used in most European universities up till the XVII century as the main textbook on astronomy brought him big fame. The book was the source of knowledge both for scientists and ordinary people interested in the matters of the world structure. So, the great Italian poet of the XIII century Dante Aligueri made use of the cosmography by Ahmad al-Farghoni, in his poetry work “The Feast”.
One of the craters on the Moon is called «Alfraghanus » (from XVII century). It was in 1998 when on the initiative of the President Islam Karimov and at the support from UNESCO, we widely celebrated the 1200th birthday of Ahmad al-Farghoni. The Ferghana State University was named after A. Farghoni. In 2007, when the President of Uzbekistan was in Egypt on the official visit, a monument to Ahmad al-Farghony was mounted on the island of Raud.