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Nur ad-Din al-Bitruji () (also spelled Nur al-Din Ibn Ishaq al-Betrugi and Abu Ishâk ibn al-Bitrogi) (known in the West by the
Latinized name Latinisation (or Latinization) of names, also known as onomastic Latinisation, is the practice of rendering a ''non''-Latin name in a Latin style. It is commonly found with historical proper names, including personal names and toponyms, and in t ...
of Alpetragius) (died c. 1204) was an Iberian-Arab
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, natural satellite, moons, comets and galaxy, g ...
and a
Qadi A qāḍī ( ar, قاضي, Qāḍī; otherwise transliterated as qazi, cadi, kadi, or kazi) is the magistrate or judge of a '' sharīʿa'' court, who also exercises extrajudicial functions such as mediation, guardianship over orphans and mino ...
in
al-Andalus Al-Andalus DIN 31635, translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label=Berber languages, Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, ...
. Al-Biṭrūjī was the first astronomer to present a non-Ptolemaic astronomical system as an alternative to Ptolemy's models, with the planets borne by geocentric spheres. Another original aspect of his system was that he proposed a physical cause of celestial motions. His alternative system spread through most of Europe during the 13th century. The crater Alpetragius on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
is named after him.


Life

Almost nothing about his life is known, except that his name probably derives from
Los Pedroches Los Pedroches is a natural region and comarca in Córdoba Province, Andalusia, southern Spain. It is located in the Sierra Morena area at the northern end of the province. The main town is Pozoblanco. The climate of the comarca is continental. I ...
(al-Biṭrawsh), a region near Cordoba. He was a disciple of
Ibn Tufail Ibn Ṭufail (full Arabic name: ; Latinized form: ''Abubacer Aben Tofail''; Anglicized form: ''Abubekar'' or ''Abu Jaafar Ebn Tophail''; c. 1105 – 1185) was an Arab Andalusian Muslim polymath: a writer, Islamic philosopher, Islamic theolo ...
(Abubacer) and was a contemporary of
Averroes Ibn Rushd ( ar, ; full name in ; 14 April 112611 December 1198), often Latinized as Averroes ( ), was an Andalusian polymath and jurist who wrote about many subjects, including philosophy, theology, medicine, astronomy, physics, psycholog ...
.


Planetary model

Al-Bitruji proposed a theory on
planetary motion In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a ...
in which he wished to avoid both epicycles and eccentrics, and to account for the phenomena peculiar to the wandering stars, by compounding
rotation Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...
s of homocentric spheres. This was a modification of the system of planetary motion proposed by his predecessors,
Ibn Bajjah Abū Bakr Muḥammad ibn Yaḥyà ibn aṣ-Ṣā’igh at-Tūjībī ibn Bājja ( ar, أبو بكر محمد بن يحيى بن الصائغ التجيبي بن باجة), best known by his Latinised name Avempace (;  – 1138), was an A ...
(Avempace) and
Ibn Tufail Ibn Ṭufail (full Arabic name: ; Latinized form: ''Abubacer Aben Tofail''; Anglicized form: ''Abubekar'' or ''Abu Jaafar Ebn Tophail''; c. 1105 – 1185) was an Arab Andalusian Muslim polymath: a writer, Islamic philosopher, Islamic theolo ...
(Abubacer). He was unsuccessful in replacing
Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...
's planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model, because of the difficulty of mapping Ptolemy's epicyclic model onto
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
's concentric spheres. It was suggested based on the Latin translations that his system is an update and reformulation of that of
Eudoxus of Cnidus Eudoxus of Cnidus (; grc, Εὔδοξος ὁ Κνίδιος, ''Eúdoxos ho Knídios''; ) was an ancient Greek astronomer, mathematician, scholar, and student of Archytas and Plato. All of his original works are lost, though some fragments are ...
combined with the motion of fixed stars developed by al-Zarqālī. However, it is not known whether the Andalusian cosmologists had access or knowledge of Eudoxus works. One original aspects of al-Biṭrūjī's system is his proposal of a physical cause of celestial motions. He combines the idea of " impetus" (first proposed by
John Philoponus John Philoponus (Greek: ; ; c. 490 – c. 570), also known as John the Grammarian or John of Alexandria, was a Byzantine Greek philologist, Aristotelian commentator, Christian theologian and an author of a considerable number of philosophical tre ...
) and the concept of ("desire"), of Abū al‐Barakāt al‐Baghdādī, to explain how energy is transferred from a first mover placed in the 9th sphere to other spheres, explaining the other spheres' variable speeds and different motions. He contradicts the Aristotelian idea that there is a specific kind of dynamics for each world, applying instead the same dynamics to the sublunar and the celestial worlds. His alternative system spread through most of Europe during the 13th century, with debates and refutations of his ideas continued up to the 16th century.
Copernicus Nicolaus Copernicus (; pl, Mikołaj Kopernik; gml, Niklas Koppernigk, german: Nikolaus Kopernikus; 19 February 1473 – 24 May 1543) was a Renaissance polymath, active as a mathematician, astronomer, and Catholic canon, who formulated ...
cited his system in the ''
De revolutionibus ''De revolutionibus orbium coelestium'' (English translation: ''On the Revolutions of the Heavenly Spheres'') is the seminal work on the heliocentric theory of the astronomer Nicolaus Copernicus (1473–1543) of the Polish Renaissance. The book, ...
'' while discussing theories of the order of the inferior planets.


Works

Al-Bitruji wrote ''Kitāb al-Hayʾah'' (The book of theoretical astronomy/cosmology,
Arabic Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...
, كتاب الهيئة), which presented criticism of Ptolomy's ''
Almagest The ''Almagest'' is a 2nd-century Greek-language mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy ( ). One of the most influential scientific texts in history, it canoni ...
'' from a physical point of view. It was well known in Europe between the 13th and the 16th centuries, and was regarded as a valid alternative to Ptolemy's ''Almagest'' in scholastic circles. This work was translated into
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
by
Michael Scot Michael Scot (Latin: Michael Scotus; 1175 – ) was a Scottish mathematician and scholar in the Middle Ages. He was educated at Oxford and Paris, and worked in Bologna and Toledo, where he learned Arabic. His patron was Frederick II of the H ...
in 1217 as ''De motibus celorum'' Pederson, Olaf. (1978) Science in the Middle Ages. ed. by David Lindberg. Chicago: Chicago University Press. p. 321 (first printed in
Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...
in 1531). A Hebrew translation by
Moses ibn Tibbon Moses ibn Tibbon (born in Marseille; flourished between 1240 and 1283) was a Jewish physician, author and translator in Provence. The number of works written by Moses ibn Tibbon suggest that he reached a great age. He was the son of Samuel ibn Tibb ...
was done in 1259. There is also an anonymous treatise on
tides Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can ...
(Escorial MS 1636, dated 1192) which contains material seemingly borrowed from al-Bitruji.


Notes


References

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Further reading

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Helaine Selin Helaine Selin (born 1946) is an American librarian, historian of science, author and the editor of several bestselling books. Career Selin attended Binghamton University, where she earned her bachelor's degree. She received her MLS from SUNY Alb ...
, ''Encyclopaedia of the history of science, technology, and medicine in non western cultures'', p. 160 {{Authority control 12th-century births 1204 deaths 12th-century Arabs 13th-century Arabs Astronomers of Al-Andalus Scholars of Al-Andalus 12th-century philosophers Islamic philosophers Year of birth unknown 12th-century astronomers Philosophers of Al-Andalus 12th-century Al-Andalus writers