Avraham Zacuto

Avraham ben Shmuel Zacuto (1452–c. 1515) was a Sephardic rabbi, astronomer, mathematician, and historian born in Salamanca, Castile. His principal astronomical work, Ha-Ḥibbur ha-Gadol ("The Great Composition"), was finished around 1478 and laid out sixty-five tables for calculating celestial positions; tradition also credits him with a metal astrolabe for use at sea. Portuguese navigators drew solar tables from his almanac; later chronicles add that Vasco da Gama consulted him before sailing for India in 1497, though modern historians of astronomy doubt he worked on navigation directly. Zacuto served as court astronomer under John II of Portugal, continuing into the early reign of Manuel I. Exiled from Spain in the 1492 expulsion, he settled in Lisbon; when forced conversions began in Portugal, he fled to Tunis, where in 1504 he finished Sefer ha-Yuḥasin, a chronicle of Jewish history reaching from Creation to 1500. He afterward set out for the Land of Israel, dying around 1515 — by most accounts in Jerusalem, though some sources say Damascus.