Abraham Zacuto ( he, , translit=Avraham ben Shmuel Zacut, pt, Abraão ben Samuel Zacuto; 12 August 1452 – ) was a Castilian

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either obse ...

astrologer Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Dif ...

, mathematician, rabbi and historian who served as Royal Astronomer to King John II of Portugal. His

astrolabe An astrolabe ( grc, ἀστρολάβος ; ar, ٱلأَسْطُرلاب ; persian, ستاره‌یاب ) is an ancient astronomical instrument that was a handheld model of the universe. Its various functions also make it an elaborate inclin ...

of copper, his astronomical tables and maritime charts played an important role in the Spanish and Portuguese navigation capability. They were used by Vasco Da Gama and Christopher Columbus. The crater Zagut on the Moon is named after him.

Life

Zacuto was born in Salamanca, Castile in 1452. He may have studied and taught

astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galax ...

at the University of Salamanca. He later taught astronomy at the universities of Zaragoza and then

Carthage Carthage was the capital city of Ancient Carthage, on the eastern side of the Lake of Tunis in what is now Tunisia. Carthage was one of the most important trading hubs of the Ancient Mediterranean and one of the most affluent cities of the classi ...

. He was well versed in Jewish Law, and was the rabbi of his community. With the

Catholic Monarchs of Spain The Catholic Monarchs were Queen Isabella I of Castile and King Ferdinand II of Aragon, whose marriage and joint rule marked the ''de facto'' unification of Spain. They were both from the House of Trastámara and were second cousins, being bo ...

issuing the 1492

Alhambra Decree The Alhambra Decree (also known as the Edict of Expulsion; Spanish: ''Decreto de la Alhambra'', ''Edicto de Granada'') was an edict issued on 31 March 1492, by the joint Catholic Monarchs of Spain (Isabella I of Castile and Ferdinand II of Arago ...

ordering the expulsion of the Jews, Zacuto took refuge in Lisbon, Portugal. Already famous in academic circles, he was invited to court and nominated Royal Astronomer and Historian by King John II of Portugal, a position which he held until the early reign of

Manuel I Manuel I may refer to: *Manuel I Komnenos, Byzantine emperor (1143–1180) *Manuel I of Trebizond, Emperor of Trebizond (1228–1263) *Manuel I of Portugal Manuel I (; 31 May 146913 December 1521), known as the Fortunate ( pt, O Venturoso), was ...

. He was consulted by the king on the possibility of a sea route to India, 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 persecution of Jews and Muslims by Manuel I of Portugal). Zacuta first fled to Tunis and later moved to Jerusalem. He probably died in 1515 in Jerusalem; however, other reports indicate his final home was the Jewish community of Damascus and his death occurred in 1520. However, in a similar vein to other giants of the Jewish faith, such as Saadia Gaon, Maimonides and the Vilna Gaon, he followed the extremely old Jewish custom (believed to have begun in the

Babylonian captivity The Babylonian captivity or Babylonian exile is the period in Jewish history during which a large number of Judeans from the ancient Kingdom of Judah were captives in Babylon, the capital city of the Neo-Babylonian Empire, following their defea ...

) of being buried as close to Jerusalem as possible. Zacuto had established his wish to make his death pilgrimage at a Passover gathering.

Work

''Ha-ḥibbur ha-gadol''

Zacuto developed a new type of

, specialized for practical determination of

latitude In geography, latitude is a coordinate that specifies the north–south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pole ...

while at sea, in contrast to earlier multipurpose devices 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 (; ; ) is a Northwest Semitic language of the Afroasiatic language family. Historically, it is one of the spoken languages of the Israelites and their longest-surviving descendants, the Jews and Samaritans. It was largely preserved ...

, with the title ''Ha-ḥibbur ha-gadol'' ("The Great Book"), begun around 1470 and completed in 1478."Zacuto, Abraham" in Glick, T., S.J. Livesy and F. Williams, editors, (2005) ''Medieval science, technology, and medicine: an encyclopedia'', New York Routledge. It was composed of 65 detailed astronomical tables (

ephemerides In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly ve ...

), with

radix In a positional numeral system, the radix or base is the number of unique digits, including the digit zero, used to represent numbers. For example, for the decimal/denary system (the most common system in use today) the radix (base number) is t ...

set in year 1473 and the

meridian Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon * ...

at Salamanca, charting the positions of the Sun, Moon and five planets. The calculations were based on the Alfonsine Tables and the works of earlier astronomers (notably of the 14th-century

Majorcan school "Majorcan cartographic school" is the term coined by historians to refer to the collection of predominantly Jewish cartographers, cosmographers and navigational instrument-makers and some Christian associates that flourished in Majorca in the 13 ...

). 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 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 translation, and arranged for its publication in 1496 by Samuel d'Ortas in

Leiria Leiria (; cel-x-proto, ɸlāryo) is a city and municipality in the Central Region of Portugal. It is the 2nd largest city in that same region, with a municipality population of 128,640 (as of 2021) in an area of . It is the seat of its own dist ...

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

''Biur luḥot''

Zacuto's ''Almanach perpetuum'' (or ''Biur luḥot'') 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) by recourse to the quadrant and the Pole Star. But this proved less useful as they approached the equator and the Pole Star began to disappear into the horizon. Zacuto's ''Almanach'' supplied the first accurate table of solar

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

, 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

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

allowed navigators to take accurate readings anywhere. Already in 1497, Vasco da Gama 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 and India. Vasco da Gama and his crew underwent a thorough briefing and preparation by Zacuto, in addition to learning to use the new instruments which he had developed for their trip before setting on the voyage to India in 1496. Prior to that, Zacuto had again improved on the existing astronomical tables, mostly those prepared under King Alphonso X of Castille. Already

Columbus Columbus is a Latinized version of the Italian surname "''Colombo''". It most commonly refers to: * Christopher Columbus (1451-1506), the Italian explorer * Columbus, Ohio, capital of the U.S. state of Ohio Columbus may also refer to: Places ...

had used Zacuto's tables. The story is that on one of his voyages, when attacked by the natives, Columbus noted that Zacuto had predicted an eclipse for that day, and used this information to threaten the natives and convince them that he could extinguish the Sun and Moon and deprive them of all light. Zacuto's work thus saved the Admiral's life and that of his crew.

Other publications

In 1504, while in Tunisia, 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, uncensored, edition was published by

Herschell Filipowski Herschell E. Filipowski (1816 – 12 June 1872), also known as Tzvi Hirsh Filipowski (, ), was a Lithuanian-born British Jewish Hebraist, editor, mathematician, linguist and actuary. Biography Early life Herschell Filipowski was born in V ...

in London at 1857.

Legacy

Abraham Zacuto might have an uncredited appearance in

Luís de Camões Luís Vaz de Camões (; sometimes rendered in English as Camoens or Camoëns, ; c. 1524 or 1525 – 10 June 1580) is considered Portugal's and the Portuguese language's greatest poet. His mastery of verse has been compared to that of Shakespear ...

's 1572 epic poem, ''

Os Lusíadas ''Os Lusíadas'' (), usually translated as ''The Lusiads'', is a Portuguese epic poem written by Luís Vaz de Camões ( – 1580) and first published in 1572. It is widely regarded as the most important work of Portuguese-language literature ...

'', as "

the Old Man of Restelo ''The Old Man of Restelo'' ( pt, Velho do Restelo), also known as ''The Old Man of Belem'', is a fictional character introduced by the Portuguese epic poet Luís de Camões in Canto IV of his work ''Os Lusíadas'' ("The Lusiads"). The Old Man ...

", a

Cassandra Cassandra or Kassandra (; Ancient Greek: Κασσάνδρα, , also , and sometimes referred to as Alexandra) in Greek mythology was a Trojan priestess dedicated to the god Apollo and fated by him to utter true prophecies but never to be belie ...

-like character that surges forward just before Vasco da Gama's departure to chide the vanity of fame and warn of the travails that await him (Canto IV, v.94-111). This may be Camões' poetic interpretation of an alleged meeting reported in

Gaspar Correia Gaspar Correia (1492 – c. 1563 in Goa) was a Portuguese historian considered a Portuguese Polybius. He authored ''Lendas da Índia'' (Legends of India), one of the earliest and most important works about Portuguese rule in Asia.Belém beach just before his fleet's departure, in which Zacuto reportedly gave Gama some final navigational tips and warned him of dangers to avoid. The small Abraham Zacuto Portuguese Jewish Museum ( pt, Museu Luso-Hebraico Abraão Zacuto)—founded in 1939 and located in the former Synagogue of Tomar—is named after Zacuto.

Bibliography

* 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 Messiah would come in 1503/4. * after 1498, ''Mishpetei ha-'istagnin (Judgments of the astrologer)''

References

External links

Biography, introduction and partial English translation of Sefer YohassinShort biography of Rabbi Abraham ZacutoJewishEncyclopediaA downloadable copy of Sefer haYuchasin printing from the middle of the 19th centuryZacuto Foundation commemorates life and works of Rabbi Abraham Zacuto and his Book of Lineage.
{{DEFAULTSORT:Zacuto, Abraham 1452 births 1515 deaths 15th-century astrologers 15th-century Spanish astronomers 15th-century Spanish mathematicians 15th-century Portuguese rabbis 16th-century astrologers 16th-century Sephardi Jews Court Jews Hebrew-language chronicles Jewish historians Jewish refugees Jews expelled from Spain in 1492 Rabbis from the Mamluk Sultanate Medieval Portuguese astrologers Medieval Portuguese astronomers Medieval Jewish astrologers Medieval Jewish astronomers People from Salamanca 16th-century Portuguese mathematicians Portuguese refugees University of Salamanca alumni University of Salamanca faculty 15th-century Portuguese historians 15th-century Spanish writers 15th-century businesspeople 16th-century businesspeople Jewish astronomers Sephardi Jews in the Mamluk Sultanate 16th-century Portuguese rabbis 16th-century rabbis from the Ottoman Empire