From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 95-96

Courtesy of

Bar iyya: Abraham Bar iyya Savasorda

Y. Tzvi Langermann

BornBarcelona, (Spain), 1070


Bar iyya is credited with writing the first works in Hebrew on astronomy and mathematics. He held several official positions in Barcelona, although that city was under Christian control. Bar iyya was fluent in Arabic, the leading language of science at the time. In response to requests from his Jewish coreligionists in Provence, Bar iyya produced a series of Hebrew texts in astronomy and mathematics, the first of their kind to be written in that language. He also created an entirely new Hebrew technical terminology. His urat ha‐Aretz (Form of the earth) is a representative of a nontechnical exposition of astronomy genre that was immensely popular in the medieval period, especially among the Hebrew reading public. Bar iyya also compiled a set of tables, known as Luot ha‐Nasi (Nasi being one of the titles borne by Bar iyya) or the Jerusalem Tables. These tables are for the most part based upon the tables of Battānī. However, some manuscripts (for example, Chicago, Newberry College, MS. Or 101) have appended to them a set of short essays and accompanying tables. These addenda have never been properly studied; one of them, which investigates the differences between the tables of Ptolemy and Battānī, may be of particular interest. Bar iyya's tables were later used by Abraham ibn ʿEzra; some manuscripts, such as the one just mentioned, bear tables of Ibn ʿEzra as well as some glosses by students of the latter.

Selected References

Goldstein, Bernard R. (1980). “Star Lists in Hebrew.” Centaurus 28: 185–208. (Publishes lists of astrolabe stars from Bar Ḥiyya's tables.)

Langermann, Y. Tzvi (1999). “Science in the Jewish Communities of the Iberian Peninsula.” In The Jews and the Sciences in the Middle Ages. Aldershot: Ashgate. (General assessment of Bar iyya's work and impact, with full references to publications of his texts in Spanish or Catalan by J. M. Millás‐Vallicrosa.)

——— (2000). “Hebrew Astronomy: Deep Soundings from a Rich Tradition.” In Astronomy Across Cultures, edited by Helaine Selin, pp. 555–584. Dordrecht: Kluwer Academic Publishers. (Discussion of utilization of Bar iyya's tables by Ibn ʿEzra and his students.)