Rabbi Abraham Zacuto was born in Salamanca, Spain in 1452. He studied Tora with his father Shemuel Zacuto and with rabbi Isaac Abohab. He was a great Tora scholar, very well versed in Talmud, Jewish Law, Philosophy and Mysticism. He also studied astronomy in the famous university of Salamanca and taught in the universities of Zaragoza and Cartagena.
In 1492, when the Jews were expelled from Spain he fled to Portugal. The Portuguese King Joao the 2nd appointed him as the Royal Astronomer and the Historian of the court. In 1497, upon the arrival of the new King Manuel, the Jews of Portugal underwent a forced conversion, in other words, they were declared Christians by Royal decree, and if found practicing Judaism they would be killed by the Inquisition in the infamous Autos de Fe. He fled to Tunis and later on managed to arrive to Jerusalem, where he died in 1515 (Other versions have him living his final days in Damascus, Syria).
Rabbi Abraham Zacuto engaged in astronomical research, an indispensable knowledge for navigating the seas. In 1478 he wrote his major astronomical work, Ha-Ḥibbur ha-Gadol. This book along with other books and treatises on astronomy (e.g., "On the solar and lunar eclipses") were translated to Spanish and Latin. In 1496 the King Joao sought his advice before sending Vasco da Gama on his sea expedition to India, around the Southern coast of Africa. Rabbi Zacuto prepared the naval-astronomical calculations. He instructed the expedition to use his newly perfected astrolabe (an astrolabe capable to determine latitude while at sea) and his maritime tables and charts, especially the Almanach Perpetuum (or Biur Luhoth) which revolutionized ocean navigation.
Rabbi Zacuto wrote many Tora books as well. His most famous book in Hebrew is called sefer yohasin (ספר יוחסין) "The book of lineage", a superb book of Jewish history since Biblical times until his own days. Click here to download one of the first editions of the book.
For a very good English edition of Sefer Yohassin see this (Check the especial offer of the Kindle edition for 0.99$ ).
For a more comprehensive biography of RABBI ABRAHAM ZACUTO see www.zacuto.org, a website founded by Dr. Vladimir Rozenblit, a 20th generation direct descendant of Rabbi Zacuto.
Rabbi Abraham Zacuto's signature
For his contributions in Astronomy, the crater Zagut on the Moon is named after Rabbi Abraham Zacuto.
There are many fascinating stories about Rabbi Abraham Zacuto's involvement with Christopher Columbus. We know that Columbus knew and used Zacuto's tables in his expedition to the Indias (America). Rabbi Zacuto was also instrumental in raising a big loan for Columbus expeditions from Abraham Senior and he introduced the unknown Columbus to Rabbi Don Isaac Abarbanel who arranged for the navigator's audience with the King and the Queen. Columbus set sail to America, bearing the Zacuto tables with him. Zacuto's tables saved Columbus life. During Columbus' last voyage to America, in February 1504, his small fleet was marooned on Jamaica, where the natives did not want to supply him and his sailors with food. The tables predicted that on February 29, 1504 it will be a lunar eclipse. Columbus assembled the Caciques (as the native chiefs were called) and threatened them that he will banish the moonlight completely if they would not give food. The eclipse frightened the natives and they asked Columbus to save the moon. Columbus acquiesced, the eclipse passed and since then the Caciques respected him and provided with all he needed.
The descents of the Zacuto family insist that a son of rabbi Abraham Zacuto sailed with Columbus and accompanied him in all his journeys. If so, this young man was the first Jew on the American soil