Ibn Ṭufayl [Latin: Abubacer] was one of the Spanish philosophers who objected to major parts of the Ptolemaic system. He seems to have worked for local rulers until reaching the post of secretary to the governor of Ceuta and Tangier, thus entering the service of the Almohads, the North African dynasty that ruled al-Andalus and North Africa from the middle of the 12th c. onwards. He then became court physician and counselor to the caliph Abū Ya`qūb Yūsuf, a sovereign who loved and supported science and thought. We know that he inspired Ibn Rushd’s systematic commentary of Aristotle and, perhaps, his writing of a medical manual. As for astronomy, Biṭrūjī informs us in his Kitāb al-Hay’a that Ibn Ṭufayl conceived a cosmological system (hay’a) that described planetary motion without having recourse to Ptolemaic eccentrics and epicycles. Ibn Ṭufayl was aware of the works of Ibn Bājja. Ibn Ṭufayl’s most important work, the philosophical romance Risālat Ḥayy ibn Yaqẓān, has several references to astronomy. [BEA, Forcada]