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Al-Ṣābiʾ Thābit ibn Qurrah al-Ḥarrānī (Arabic: ثابت بن قره‎, Latin: Thebit/Thebith/Tebit;^[2] 826^[3] – February 18, 901) was a Arab^[4][5]Sabian mathematician, physician, astronomer, and translator who lived in Baghdad in the second half of the ninth century during the time of Abbasid Caliphate.

Thābit ibn Qurrah made important discoveries in algebra, geometry, and astronomy. In astronomy, Thābit is considered one of the first reformers of the Ptolemaic system, and in mechanics he was a founder of statics.^[3]

Biography

Al-Jazira region and its subdivisions (Diyar Bakr, Diyar Mudar, and Diyar Rabi'a) during the Abbasid Caliphate

Thābit was born in Harran in Upper Mesopotamia, which at the time was part of the Diyar Mudar subdivision of the al-Jazira region of the Abbasid Caliphate. The city of Harran was never fully Christianized. By the early Muslim conquests, the people of Harran were still adhering to the cult of Sin.

Thābit and his pupils lived in the midst of the most intellectually vibrant, and probably the largest, city of the time, Baghdad. He occupied himself with mathematics, astronomy, astrology, magic, mechanics, medicine, and philosophy. Later in his life, Thābit's patron was the Abbasid Caliph al-Mu'tadid (reigned 892–902). Thābit became the Caliph's personal friend and courtier.

Thābit died in Baghdad. After him, the greatest Sabean name was al-Battani.^{[citation needed]}

Translation

Pages from Thābit's Arabic translation of Apollonius' Conics

Thābit's native language was Syriac,^[6] which was the eastern Aramaic variety from Edessa, and he was fluent in both Greek and Arabic.

Thābit translated from Greek into Arabic works by Apollonius of Perga, Archimedes, Euclid and Ptolemy. He revised the translation of Euclid's Elements of Hunayn ibn Ishaq. He also rewrote Hunayn's translation of Ptolemy's Almagest and translated Ptolemy's Geography. Thābit's translation of a work by Archimedes which gave a construction of a regular heptagon was discovered in the 20th century, the original having been lost.^{[citation needed]}

Astronomy

The medieval astronomical theory of the trepidation of the equinoxes is often attributed to Thābit.^{[citation needed]} But it had already been described by Theon of Alexandria in his comments of the Handy Tables of Ptolemy. According to Copernicus, Thābit determined the length of the sidereal year as 365 days, 6 hours, 9 minutes and 12 seconds (an error of 2 seconds). Copernicus based his claim on the Latin text attributed to Thābit. Thābit published his observations of the Sun.^{[citation needed]}

Mathematics

In mathematics, Thābit discovered an equation for determining amicable numbers. He also wrote on the theory of numbers, and extended their use to describe the ratios between geometrical quantities, a step which the Greeks did not take.

He is known for having calculated the solution to a chessboard problem involving an exponential series.^[7]

He computed the volume of the paraboloid.^[8]

He also described a generalization of Pythagoras' theorem.^[9]

Physics

In physics, Thābit rejected the Peripatetic and Aristotelian notions of a "natural place" for each element. He instead proposed a theory of motion in which both the upward and downward motions are caused by weight, and that the order of the universe is a result of two competing attractions (jadhb): one of these being "between the sublunar and celestial elements", and the other being "between all parts of each element separately".^[10] and in mechanics he was a founder of statics.^[3]

Works

Only a few of Thābit's works are preserved in their original form.

• 
  On the Sector-Figure which deals with Menelaus' theorem.^[11]


• 
  On the Composition of Ratios^[11]

Eponyms

• Thabit number


• Thebit (crater)

References

Further reading

• Roshdi Rashed (ed.), Thābit ibn Qurra. Science and Philosophy in Ninth-Century Baghdad, Berlin, Walter de Gruyter, 2009.


• Francis J. Carmody: The astronomical works of Thābit b. Qurra. 262 pp. Berkeley and Los Angeles: University of California Press, 1960.


• 
  Rashed, Roshdi (1996). Les Mathématiques Infinitésimales du IXe au XIe Siècle 1: Fondateurs et commentateurs: Banū Mūsā, Ibn Qurra, Ibn Sīnān, al-Khāzin, al-Qūhī, Ibn al-Samḥ, Ibn Hūd. London. Reviews: Seyyed Hossein Nasr (1998) in Isis 89 (1) pp. 112-113; Charles Burnett (1998) in Bulletin of the School of Oriental and African Studies, University of London 61 (2) p. 406.


• Churton, Tobias. The Golden Builders: Alchemists, Rosicrucians, and the First Freemasons. Barnes and Noble Publishing, 2006.


• Hakim S Ayub Ali. Zakhira-i Thābit ibn Qurra (preface by Hakim Syed Zillur Rahman), Aligarh, India, 1987.

External links

• 
  Palmeri, JoAnn (2007). "Thābit ibn Qurra". In Thomas Hockey; et al. The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 1129–30. ISBN 978-0-387-31022-0. (PDF version)


• 
  O'Connor, John J.; Robertson, Edmund F., "Al-Sabi Thabit ibn Qurra al-Harrani", MacTutor History of Mathematics archive, University of St Andrews.


• 
  Rosenfeld, B. A.; Grigorian, A. T. (2008) [1970-80]. "Thābit Ibn Qurra, Al-Ṣābiʾ Al-Ḥarrānī". Complete Dictionary of Scientific Biography. Encyclopedia.com.
  


• Thabit ibn Qurra on Astrology & Magic