Abraham Zacuto, the astronomer who predicted an eclipse and saved Columbus’s life

Home »Technology» Abraham Zacuto, the astronomer who predicted an eclipse and saved the life of Columbus on December 26, 2021

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Update: 12/26/2021 00: 47h


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In the Middle Ages, religion permeated all aspects of society and different communities learned to live together and share the same spaces. It was not an easy task, especially for the Jewish communities which alternated permissive moments with other intolerant and repressive ones.

This situation was not an obstacle for them to leave us an enormous cultural baggage. In some aljamas science, literature, theater, philosophy, theology… have experienced a real revolution.

In the Middle Ages, astronomers, as a rule, offered a product based on astrological prediction, which did not prevent them from being used by some monarchs to make serious political decisions.

Portrait of Abraham Zacuto – Spanish Foundation for Science and Technology, Eulogia Merle

In the middle of the 15th century, Abraham Zacuto (1452-1515) was born in Salamanca, an eminent astronomer and mathematician called to revolutionize ocean navigation.

He belonged to a family of French exiles, his grandfather fled the anti-Semitic laws dictated by the Frankish king Philippe le Bel and in 1306, after crossing the Pyrenees, he settled on the Castilian plateau.

Abraham’s father served as rabbi on the banks of the Tormes, which allowed him to benefit from a privileged education and to develop his scientific concerns. Around 1475 he published ‘Composition Magna’ a complex work in which they appear astronomical tables, calculated for the meridian of Salamanca, which corrected the errors of the “Alphonsine tables”.

The interest of Jewish scientists in astronomy was due to the fact that it allowed them to accurately determine the time of the appearance of the new moon, which marked the beginning of the Sabbath and the beginning of the new year.

A scientist at the Portuguese court

Zacuto was a strong advocate of the role astronomy played in preserving health, arguing that zodiac signs influenced every part of the body and their knowledge helped physicists determine the prognosis for certain diseases.

In 1492, with the expulsion of the Jews, Zacuto emigrated to Portugal, where King John II appointed him royal astronomer and court historian. His successor to the throne, Manuel I, asks him for advice on an expedition with which he plans to reach India bypassing the southern cone of the African continent.

Apparently the Hebrew gave a favorable opinion, pointing out that the stars indicated that the success of the company depended on two brothers leading the expedition. It seems that this detail was decisive for Vasco da Gama, the senior naval captain, was chosen because he had a brother.

It is said that Zacuto prepared the maritime and astronomical calculations that made the expedition possible and that in addition, he trained the crew in the use of an astrolabe of his creation and which made it possible to determine the geographical latitude. when browsing.

In 1496, he published a version of the “Composition Magna” under the title “Almanac perpetuel” which enjoyed enormous notoriety for more than a century.

The success of the shipping company under the Portuguese flag was not an obstacle so that in 1497, in the context of a new anti-Semitic wave in Lusitanian lands, he had to emigrate to North Africa, from where he would go to Damascus. , the city that finally saw it. Pass away.

The saving eclipse

Christopher Columbus personally met Zacuto and used his maritime tables during the expedition to India. It collected the solar declination – angle formed by the sun’s rays with the plane of the equator – which made it possible to determine with enormous precision the position in relation to the equator, without having to resort to the polar star.

During the last Colombian voyage in February 1504, the fleet was left to fend for itself in Jamaica, where the natives refused to provide them with food. Zacuto’s tables predicted a lunar eclipse for February 29. The admiral assembled the chiefs of the islands and threatened to wipe out the moon if their needs were not met. Apparently, the lunar eclipse scared the natives so much that they not only respected the lives of the sailors, but also provided them with whatever they asked for.

Mr. Jara

Pedro Gargantilla is an internist at the Hospital de El Escorial (Madrid) and author of several popular books.

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