Абу Исхак аз-Заркали: Арабский астроном и создатель инструментов

Muslim astrologer, and astronomer

Abū Isḥāq Ibrāhīm ibn Yaḥyā al Naqqāsh al Zarqālī al Tujibi (إبراهيم بن يحيى الزرقالي); also known as Al Zarkali or Ibn Zarqala (1029–1100), was an Arab maker of astronomical instruments and an astrologer from the western part of the Islamic world. In Latin he was referred to as Arzachel or Arsechieles, a modified form of Arzachel, meaning 'the engraver'. He lived in Toledo, Al Andalus before moving to Córdoba later in his life. His works inspired a generation of Islamic astronomers in Al Andalus, and later, after being translated, were very influential in Europe. His invention of the Saphaea (a perfected astrolabe) proved very popular and was widely used by navigators until the 16th century. The crater Arzachel on the Moon is named after him. was born in a village near the outskirts of Toledo, the then capital of the newly established Taifa of Toledo. He started work after 1048 under Said al Andalusi for the Emir Al Mamun of Toledo and also under Al Mu'tamid of the Taifa of Seville. Assuming a leading position under Said, Al Zarqālī conducted solar observations for 25 years from 1050. He was trained as a metalsmith and due to his skills he was nicknamed Al Nekkach "the engraver of metals". His Latinized name, 'Arzachel' is formed from the Arabic al Zarqali al Naqqash, meaning 'the engraver'.

Al Zarqālī wrote two works on the construction of an instrument (an equatorium) for computing the position of the planets using diagrams of the Ptolemaic model. These works were translated into Spanish in the 13th century by order of King Alfonso X in a section of the Libros del Saber de Astronomia entitled the "Libros de las laminas de los vii planetas". He also invented a perfected kind of astrolabe known as "the tablet of al Zarqālī" (al ṣafīḥā al zarqāliyya), which was famous in Europe under the name Saphaea. There is a record of an al Zarqālī who built a water clock, capable of determining the hours of the day and night and indicating the days of the lunar months. According to a report found in al Zuhrī's Kitāb al Juʿrāfīyya, his name is given as Abū al Qāsim bin ʿAbd al Raḥmān, also known as al Zarqālī, which has made some historians think that this is a different person. Al Zarqālī's model for the motion of the Sun, in which the center of the Sun's deferent moved on a small, slowly rotating circle to reproduce the observed motion of the solar apogee, was discussed in the thirteenth century by Bernard of Verdun and in the fifteenth century by Regiomontanus and Peurbach. In the sixteenth century Copernicus employed this model, modified to heliocentric form, in his De Revolutionibus Orbium Coelestium.

Al Zarqālī also contributed to the famous Tables of Toledo, an adaptation of earlier astronomical data by Al Khwarizmi and Al Battani, to locate the coordinates of Toledo. This almanac that he compiled directly provided "the positions of the celestial bodies and need no further computation", it further simplifies longitudes using planetary cycles of each planet. In designing an instrument to deal with Ptolemy's complex model for the planet Mercury, in which the center of the deferent moves on a secondary epicycle, al Zarqālī noted that the path of the center of the primary epicycle is not a circle, as it is for the other planets. Instead it is approximately oval and similar to the shape of a pignon (or pine nut). Some writers have misinterpreted al Zarqālī's description of an earth centered oval path for the center of the planet's epicycle as an anticipation of Johannes Kepler's sun centered elliptical paths for the planets. Although this may be the first suggestion that a conic section could play a role in astronomy, al Zarqālī did not apply the ellipse to astronomical theory and neither he nor his Iberian or Maghrebi contemporaries used an elliptical deferent in their astronomical calculations.