Abraham Zacuto

Abraham Zacuto

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Abraham Zacuto (August 12, 1452 – probably 1515) was a Sephardi Jewish
Sephardi Jews
Sephardi Jews is a general term referring to the descendants of the Jews who lived in the Iberian Peninsula before their expulsion in the Spanish Inquisition. It can also refer to those who use a Sephardic style of liturgy or would otherwise define themselves in terms of the Jewish customs and...

 astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

, astrologer
Astrologer
An astrologer practices one or more forms of astrology. Typically an astrologer draws a horoscope for the time of an event, such as a person's birth, and interprets celestial points and their placements at the time of the event to better understand someone, determine the auspiciousness of an...

, mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

 and historian who served as Royal Astronomer in the 15th century to King John II of Portugal
John II of Portugal
John II , the Perfect Prince , was the thirteenth king of Portugal and the Algarves...

. The crater Zagut
Zagut (crater)
Zagut is a crater located in the heavily impacted southeast sector of the Moon. It is almost surrounded by other named craters, with Wilkins to the northwest, Lindenau to the east, Rabbi Levi in the southeast, and Celsius to the southwest....

 on the Moon is named after him.

Life


Zacuto was born in Salamanca
Salamanca
Salamanca is a city in western Spain, in the community of Castile and León. Because it is known for its beautiful buildings and urban environment, the Old City was declared a UNESCO World Heritage Site in 1988. It is the most important university city in Spain and is known for its contributions to...

, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 in 1452. He may have studied and taught astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 at the University of Salamanca
University of Salamanca
The University of Salamanca is a Spanish higher education institution, located in the town of Salamanca, west of Madrid. It was founded in 1134 and given the Royal charter of foundation by King Alfonso IX in 1218. It is the oldest founded university in Spain and the third oldest European...

. He later was for a time teacher of astronomy at the universities of Zaragoza
Zaragoza
Zaragoza , also called Saragossa in English, is the capital city of the Zaragoza Province and of the autonomous community of Aragon, Spain...

 and then Cartagena
Cartagena, Spain
Cartagena is a Spanish city and a major naval station located in the Region of Murcia, by the Mediterranean coast, south-eastern Spain. As of January 2011, it has a population of 218,210 inhabitants being the Region’s second largest municipality and the country’s 6th non-Province capital...

. He was versed in Jewish Law
Halakha
Halakha — also transliterated Halocho , or Halacha — is the collective body of Jewish law, including biblical law and later talmudic and rabbinic law, as well as customs and traditions.Judaism classically draws no distinction in its laws between religious and ostensibly non-religious life; Jewish...

, and was rabbi
Rabbi
In Judaism, a rabbi is a teacher of Torah. This title derives from the Hebrew word רבי , meaning "My Master" , which is the way a student would address a master of Torah...

 of his community.

With the general expulsion of the Jews
Alhambra decree
The Alhambra Decree was an edict issued on 31 March 1492 by the joint Catholic Monarchs of Spain ordering the expulsion of Jews from the Kingdom of Spain and its territories and possessions by 31 July of that year.The edict was formally revoked on 16 December 1968, following the Second...

 from Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 in 1492, Zacuto took refuge in Lisbon
Lisbon
Lisbon is the capital city and largest city of Portugal with a population of 545,245 within its administrative limits on a land area of . The urban area of Lisbon extends beyond the administrative city limits with a population of 3 million on an area of , making it the 9th most populous urban...

, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

. Already famous in academic circles, he was invited to court and nominated Royal Astronomer and Historian by King John II of Portugal
John II of Portugal
John II , the Perfect Prince , was the thirteenth king of Portugal and the Algarves...

, a position which he held until the early reign of Manuel I
Manuel I of Portugal
Manuel I , the Fortunate , 14th king of Portugal and the Algarves was the son of Infante Ferdinand, Duke of Viseu, , by his wife, Infanta Beatrice of Portugal...

. He was consulted by the King on the possibility of a sea route to India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, a project which he supported and encouraged. Zacuto would be one of the few who managed to flee Portugal during the forced conversions and prohibitions of departure that Manuel I enacted, in order to keep the Jews in Portugal as nominal Christians for foreign policy reasons (see History of the Jews in Portugal
History of the Jews in Portugal
The history of the Jews in Portugal reaches back over two thousand years and is directly related to Sephardi history, a Jewish ethnic division that represents communities who have originated in the Iberian Peninsula .-Before Portugal:...

). He fled first to Tunis
Tunis
Tunis is the capital of both the Tunisian Republic and the Tunis Governorate. It is Tunisia's largest city, with a population of 728,453 as of 2004; the greater metropolitan area holds some 2,412,500 inhabitants....

, and later moved to Jerusalem. He died probably in 1515 in Jersusalem, however, other reports indicate his death to occur in Damascus and the death to occur in 1520.

Work


Zacuto developed a new type of astrolabe
Mariner's astrolabe
The mariner's astrolabe, also called sea astrolabe, was an inclinometer used to determine the latitude of a ship at sea by measuring the sun's noon altitude or the meridian altitude of a star of known declination. Not an astrolabe proper, the mariner's astrolabe was rather a graduated circle with...

, specialized for practical determination of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 while at sea, in contrast to earlier multipurpose devices
Astrolabe
An astrolabe is an elaborate inclinometer, historically used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time given local latitude and longitude, surveying, triangulation, and to...

 intended for use ashore. Abraham Zacuto's principal claim to fame is the great astronomical treatise, written while he was in Salamanca, in Hebrew
Hebrew language
Hebrew is a Semitic language of the Afroasiatic language family. Culturally, is it considered by Jews and other religious groups as the language of the Jewish people, though other Jewish languages had originated among diaspora Jews, and the Hebrew language is also used by non-Jewish groups, such...

, with the title Ha-ḥibbur ha-gadol ("The Great Book"), begun around 1470 and completed in 1478. It was composed of 65 detailed astronomical tables (ephemerides
Ephemeris
An ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...

), with radix
Radix
In mathematical numeral systems, the base or radix for the simplest case is the number of unique digits, including zero, that a positional numeral system uses to represent numbers. For example, for the decimal system the radix is ten, because it uses the ten digits from 0 through 9.In any numeral...

 set in year 1473 and the meridian
Meridian (astronomy)
This article is about the astronomical concept. For other uses of the word, see Meridian.In the sky, a meridian is an imaginary great circle on the celestial sphere. It passes through the north point on the horizon, through the celestial pole, up to the zenith, through the south point on the...

 at Salamanca, charting the positions of the Sun, Moon and five planets. The calculations were based on the Alfonsine Tables
Alfonsine tables
The Alfonsine tables provided data for computing the position of the Sun, Moon and planets relative to the fixed stars....

 and the works of earlier astronomers (notably of the 14th C. Majorcan school
Majorcan cartographic school
The Majorcan cartographic school is the term coined by historians to refer to the collection of cartographers, cosmographers and navigational instrument-makers that flourished in Majorca in the 14th and 15th Centuries. The label is usually inclusive of those who worked in mainland Catalonia...

). Zacuto set out the data in a simple "almanac" format, with the positions of a planet easily interpolated between entries, making it quite easy to use.

The first Castilian
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 translation was undertaken in 1481 by Juan de Salaya. Zacuto's Portuguese disciple Joseph Vizinus (Mestre José Vizinho, the much-valued physician and advisor of John II of Portugal) adapted it into a Latin translation, under the title Tabulae tabularum Celestium motuum sive Almanach perpetuum ("Book of Tables on the celestial motions or the Perpetual Almanac"), immediately along with a new Castilian
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 translation, and arranged for its publication in 1496 by Abraão de Ortas in Leiria
Leiria
Leiria is a city in Leiria Municipality in the Centro Region, Portugal. It is the capital of Leiria District. The city proper has 50,200 inhabitants and the entire municipality has nearly 120,000...

, Portugal. (one of the first books published in Portugal with a movable type printing press).

Zacuto's Almanach perpetuum (or Biur Luhoth) helped immediately revolutionize ocean navigation. Prior to the Almanach, navigators seeking to determine their position in the high seas had to correct for "compass error" (the deviation of the magnetic north from the true north
True north
True north is the direction along the earth's surface towards the geographic North Pole.True geodetic north usually differs from magnetic north , and from grid north...

) by recourse to the quadrant
Quadrant (instrument)
A quadrant is an instrument that is used to measure angles up to 90°. It was originally proposed by Ptolemy as a better kind of astrolabe. Several different variations of the instrument were later produced by medieval Muslim astronomers.-Types of quadrants:...

 and the Pole Star
Pole star
The term "Pole Star" usually refers to Polaris, which is the current northern pole star, also known as the North Star.In general, however, a pole star is a visible star, especially a prominent one, that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent...

. But this proved less useful as they approached the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

 and the Pole Star began to disappear into the horizon. Zacuto's Almanach supplied the first accurate table of solar declination
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...

, allowing navigators to use the sun instead. As the quadrant could not be used to look directly at the sun, Portuguese navigators began using the astrolabe
Astrolabe
An astrolabe is an elaborate inclinometer, historically used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time given local latitude and longitude, surveying, triangulation, and to...

 on board (an old land-based instrument to measure the height of the sun indirectly). Zacuto's tables in conjunction with the new metal nautical astrolabe
Mariner's astrolabe
The mariner's astrolabe, also called sea astrolabe, was an inclinometer used to determine the latitude of a ship at sea by measuring the sun's noon altitude or the meridian altitude of a star of known declination. Not an astrolabe proper, the mariner's astrolabe was rather a graduated circle with...

 allowed navigators to take accurate readings anywhere. Already in 1497, Vasco da Gama
Vasco da Gama
Vasco da Gama, 1st Count of Vidigueira was a Portuguese explorer, one of the most successful in the Age of Discovery and the commander of the first ships to sail directly from Europe to India...

 took Zacuto's tables and the astrolabe with him on the maiden trip to India.. It would continue to be used by Portuguese ships thereafter to reach far destinations such as Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

.

In 1504, while in Tunisia
Tunisia
Tunisia , officially the Tunisian RepublicThe long name of Tunisia in other languages used in the country is: , is the northernmost country in Africa. It is a Maghreb country and is bordered by Algeria to the west, Libya to the southeast, and the Mediterranean Sea to the north and east. Its area...

, Abraham Zacuto wrote a history of the Jewish people, Sefer yuḥasin , since the Creation of the World until 1500, and several other astronomical/astrological treatises. The History was greatly respected and was reprinted in Cracow in 1581, at Amsterdam in 1717, and at Königsberg in 1857, while a complete edition was published by Filipowski in London at 1857. Annotations in Hebrew to chapter five of "Sefer Hayuhasin", were published by Yoel Lieberman in 2001 in a masters thesis called "A Record of Medieval Sages In Sefer Yuchasin of Rabbi Abraham Zacut". The book was translated into English and published in 2005 by the Zacuto foundation founded by Dr. Vladimir Rozenblit, a 20th generation direct descendant of Zacuto.

Publications by Zacuto

  • 1478, Ha-ḥibbur ha-gadol (La Compilación Magna), his first astronomical book, translated into Castilian 1481 by himself and Juan de Salaya from the University of Salamanca. In 1496 the work was translated into Latin translation by José Vizinho and published in Leira as Almanach Perpetuum or Tabule tabularum celestium motuum astronomi zacuti. This work became important for the contemporary explorers.
  • 1486, Tratado breve en las ynfluencias del cielo, and De los eclipses del sol y la luna.
  • 1498, Sefer yuḥasin, historical text for the Jewish people. [Digital edition: Zacuto, Avraham. Sefer yuḥasin. Brooklyn, NY: Renaissance Hebraica, 1994.]
  • 1498, astrological text predicting that the messias would come in 1503/4.
  • after 1498, Mishpetei ha-'istagnin (Judgments of the astrologer)

External links