Abd al-Rahman al-Sufi

Abd ar -Rahman as- Sufi ( born December 7, 903; † May 25 986 ), also under the name of Abd al -Rahman al - Sufi, or Abd al -Rahman Abu al -Husayn (Arabic عبد الرحمن بن عمر الصوفي DMG ʿ Abdu 'r - Rahman bin ʿ Umar aṣ SUFI ) and known in the Western world as Azophi, was a Persian astronomer.

Life and merits

He lived in Isfahan at the court of the Emir Adud ad-Daula and dealt with the works of Greek astronomers, in particular that of Claudius Ptolemy, whose " Great astronomical system " was translated into Arabic by 800 ( " Almagest ").

As- Sufi contributed to several corrections of the Ptolemaic star list, in particular through their own observations to the brightness and tried first the Greek and the traditional Arab to put stars and constellation names in relationship. He improved, inter alia, the calculation of the length of the solar year and dealt with the multiple uses of the astrolabe, an already used by Ptolemy, inherited from the Arabs astronomical instrument in disc shape with visor device that the mechanical solution of astronomical and astronomical and geographical tasks serves.

He observed that the plane of the ecliptic is inclined in relation to the celestial equator, and led by a more accurate calculation of the tropical year.

The lunar crater Azophi (diameter 47 km) and the asteroid ( 12621 ) Alsufi bear his name.

Main work

As- Sufi published his major work, The Book of fixed stars around the year 964 in Arabic, the language of education of Islam. The book provides a link from Ptolemy's Almagest, Arabic tradition and own observations dar. It contains exclusively of illustrations and descriptions of constellations of stars that comprise their position, brightness and color. The work was ordered by constellations.

In it he stated, inter alia, both the large Magellanic Cloud, which he called al -Bakr ( the white oxen ) and the Andromeda galaxy, long before the former sighted by Ferdinand Magellan became the first Europeans and the latter after the invention of the telescope in 1612 by Simon Marius was rediscovered.