Background
Almost nothing about his life is known, except that his name probably derives from Los Pedroches, a region near Cordoba. He was probably born in Pedroche, Spain, in 12th centuary.
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Nur al-Din Abu Ishaq al Bitruji
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also known as
Alpetragius
Education
He was a disciple of Ibn Tufail (Abubacer) and was a contemporary of Averroes.
Career
The problem faced by al-Bitruji was that faced by all Aristotelians who read Ptolemy's Almagest. Aristotle clearly stated that the planets must move with circular motions and implied that the center of these motions must be identical with the center of the earth; he further desired a mechanism to transfer the motion of the prime mover to the planetary spheres. Ptolemy, on the other hand, while preserving the principle of circular motions (on eccentrics and epicycles), placed the centers of these motions elsewhere than at the center of the earth; for Saturn, Jupiter, Mars, Venus, and Mercury he placed the centers of their uniform motions not at the centers of their respective eccentric deferents but at points called equants.
Eudoxus of Cnidus had already shown that it is theoretically possible to explain the two most obvious anomalies in planetary motion—retrogression and latitude—by means of homocentric spheres. Aristotle, by adding more spheres, converted this system to a mechanical model of the universe (though technical details make it impossible for such a model to yield correct predictions of the retrogressions and latitudes of Mars and Venus). Al-Bitruji followed the suggestion of Ibn Tufayl, as did the latter's other pupil Averroës, and attempted to adjust the Aristotelian solution in such a way that it would correspond to observed reality. The attempt failed owing to the inherent inadequacy of the homocentric system to describe the phenomena.
