عنوان مقاله [English]
نویسنده [English]چکیده [English]
The main problem of Ptolemaic model of the superior planets was related to the “equant point”. It is a geometrical point with respect to which the motion of the deferent sphere is uniform. But it cannot be acceptable on the basis of Aristotle's philosophy on the motions of celestial spheres. Astronomers of Maragha School devised some new models to avoid this problem, while they were in accordance with Ptolemy's observations. Qut?b al-D?n Sh?r?z? (d. 1311) has provided his own model for superior planets in his works: Nih?yat al-idr?k f? dir?yat al-afl?k and al-Tuh?fa al-Sh?h?yya in Arabic, and Ikhti?r?t-i Muz?affar? in Persian. His model in Ikhti?r?t has not been studied yet and it is different from the one introduced by Saliba (1979) and Kennedy (1966). Here, I introduce Qut?b al-D?n's model for superior planets provided in eighth chapter of the second book of Ikhti?r?t-i Muz?affar?. I also discuss a conflict between observations and the theory which this model involves.