Thābit ibn Qurra

"Thebit" redirects here. For crater on the Moon, see Thebit (crater).

Thābit ibn Qurra
Born	210-211 AH/ 826 AD Harran (now in Şanlıurfa Province, Turkey)
Died	Wednesday, 26 Safar, 288 AH / February 18, 901 AD Baghdad (now Iraq)
Academic background
Influences	Banu Musa, Archimedes, Apollonius, Nicomachus, Euclid
Academic work
Era	Islamic Golden Age
Main interests	Mathematics, Mechanics, Astronomy, Astrology, Translation, Number theory
Notable ideas	Early reformer of the Ptolemaic system A founder of statics Length of the sidereal year
Influenced	Al-Khazini, Al-Isfizari, Na'im ibn Musa

Al-Ṣābiʾ Thābit ibn Qurra al-Ḥarrānī (Arabic: ثابت بن قرة, Latin: Thebit/Thebith/Tebit; 826 – February 18, 901) was an Sabian mathematician, physician, astronomer, and translator who lived in Baghdad in the second half of the ninth century during the time of Abbasid Caliphate.

Ibn Qurra made important discoveries in algebra, geometry, and astronomy. In astronomy, Thabit is considered one of the first reformers of the Ptolemaic system, and in mechanics he was a founder of statics.

Biography

Thabit was born in Harran (known as Kharanu, "passage" in old Assyrian language) in Assyria (modern-day Turkey). The city of Harran was never fully Christianized, unlike the rest of Assyria. By the early Arabic era, the people of Harran were still adhering to the cult of Sin. Thabit 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, Thabit's patron was the Abbasid Caliph al-Mu'tadid (reigned 892–902). Thabit became the Caliph's personal friend and courtier. Thabit died in Baghdad. After him the greatest Sabean name was Abu Abdallah Mohammad ibn Jabir Al-Battani.

Translation

Pages from Thābit's Arabic translation of Apollonius' Conics

Thabit's native language was Syriac, which was the eastern Aramaic dialect from Edessa, and he was fluent in Greek and Arabic. He translated from Greek into Arabic works by Apollonius, 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. Thabit'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.

Astronomy

The medieval astronomical theory of the trepidation of the equinoxes is often attributed to Thabit. But it had already been described by Theon of Alexandria in his comments of the Handy Tables of Ptolemy. According to Copernicus Thabit 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 Thabit. Thabit published his observations of the Sun.

Mathematics

See also: Thabit number

In mathematics, Thabit 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.

He also described a Pythagoras theorem.

Physics

In physics, Thabit 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".

Works

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

• On the Sector-Figure which deals with Menelaus' theorem.
• On the Composition of Ratios

Eponyms

• Thabit number
• Thebit (crater)

Further reading

• 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.{{cite book}}: CS1 maint: location missing publisher (link) 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. (eds.). 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