Pedro Alfonso's Contribution to Astronomy

This article treats successively the following themes: biographical notes on Pedro Alfonso (Moshe Sefardi); Pedro Alfonso's classification of the sciences as presented in his Disciplina clericalis; scientific collaboration between Pedro Alfonso and Walcher of Malvern; Walcher's early studies in Oriental astronomy under the supervision P. Alfonso; closer study of these developments in medieval science; Alfonso's Epistola to the scholars of Europe; the proem to this Epistola; an analysis of the Tables or Canons of Astronomy attributed to P. Alfonso; P. Alfonso's position on astrology as presented in the introduction to that work; the relation between these Canons and the Tables of al-Khwārizmī; the problems this presents with regard to the translation by Adelard of Bath; the likelihood of a collaboration between P. Alfonso and Adelard of Bath; concluding remarks and the astronomical data contained in Pedro Alfonso's polemical work Dialogus Petri et Moysei iudei.