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Ulugh Beg

Ulugh Beg

Forensic facial reconstruction
Born c. 1393 or 1394
Sultaniyeh (Persia)
Died October 27, 1449
Occupation astronomer, mathematician and sultan
Known for trigonometry and spherical geometry
Relatives Timur, Shah Rukh

Ulugh Beg (Chaghatay/Persian: (میرزا محمد طارق بن شاه رخ (الغ‌بیگ Mīrzā Mohammad Tāregh bin Shāhrokh (Ulugh Beg) - also Uluğ Bey, Ulugh Bek and Ulug Bek) (c. 1393 or 1394 in Sultaniyeh (Persia) – October 27, 1449) was a Timurid ruler as well as an astronomer, mathematician and sultan. His commonly-known name is not truly a personal name, but rather a moniker, which can be loosely translated as "Great Ruler" or "Patriarch Ruler" and was the Turkic equivalent of Timur's Perso-Arabic title Amīr-e Kabīr[1]. His real name was Mīrzā Mohammad Tāregh bin Shāhrokh. Ulugh Beg was also notable for his work in astronomy-related mathematics, such as trigonometry and spherical geometry.


Early life

He was the grandson of the conqueror, Timur (Tamerlane) (1336-1405), and oldest son of Shah Rukh, both of whom came from the Mongol Barlas tribe of Transoxiana (now Uzbekistan). His mother was the Persian noblewoman, Goharshad. Like his grandfather, Timur, he was also the ancestor of Babur, founder of the Mughal Dynasty.

Ulugh Beg was born in Sultaniyeh in Persia. As a child he wandered through a substantial part of the Middle East and India as his grandfather expanded his conquests in those areas. With Timur's death, however, and the accession of Ulugh's father to much of the Timurid Empire, he settled in Samarkand, which had been Timur's capital. After Shah Rukh moved the capital to Herat (in modern Afghanistan), sixteen-year-old Ulugh Beg became the shah's governor in Samarkand in 1409. In 1411, he became the sovereign ruler of the whole Mavarannahr khanate.


The teenaged ruler set out to turn the city into an intellectual center for the empire. Between 1417 and 1420, he built a madrasa ("university" or "institute") on Registan Square in Samarkand, and he invited numerous Islamic astronomers and mathematicians to study there. The madrasa building still survives. Ulugh Beg's most famous pupil in mathematics was Ghiyath al-Kashi (approximately 1370-1429).

Ulugh Beg's observatory in Samarkand. In Ulugh Beg's time, these walls were lined with polished marble.


His own particular interests concentrated on astronomy, and, in 1428, he built an enormous observatory, called the Gurkhani Zij, similar to Tycho Brahe's later Uraniborg as well as Taqi al-Din's observatory in Constantinople. Lacking telescopes to work with, he increased his accuracy by increasing the length of his sextant; the so-called Fakhri sextant had a radius of about 36 meters (118 ft) and the optical separability of 180" (seconds of arc).

Using it, he compiled the 1437 Zij-i-Sultani of 994 stars, generally considered the greatest star catalogue between those of Ptolemy and Brahe, a work that stands alongside Abd al-Rahman al-Sufi's Book of Fixed Stars. The serious errors which he found in previous Arabian star catalogues (many of which had simply updated Ptolemy's work, adding the effect of precession to the longitudes) induced him to redetermine the positions of 992 fixed stars, to which he added 27 stars from Abd al-Rahman al-Sufi's catalogue Book of Fixed Stars from the year 964, which were too far south for observation from Samarkand. This catalogue, one of the most original of the Middle Ages, was edited by Thomas Hyde at Oxford in 1665 under the title Tabulae longitudinis et latitudinis stellarum fixarum ex observatione Ulugbeighi by G. Sharpe in 1767, and, in 1843, by Francis Baily in vol. xiii of the Memoirs of the Royal Astronomical Society.

In 1437, Ulugh Beg determined the length of the sidereal year as 365.2570370...d = 365d 6h 10m 8s (an error of +58s). In his measurements over many years, he used a fifty-metre-high gnomon. This value was improved by 28s 88 years later, in 1525, by Nicolaus Copernicus (1473-1543), who appealed to the estimation of Thabit ibn Qurra (826-901), which was accurate to +2s.

The above-ground portion of Ulugh Beg's observatory was destroyed shortly after his death; the surviving underground chamber was excavated in 1908 by the primary-school teacher and amateur archaeologist, Vladimir Viyatkin, later Samarkand's director of antiquities.[2]


In mathematics, Ulugh Beg wrote accurate trigonometric tables of sine and tangent values correct to eight decimal places.

Ulugh Beg and his astronomical observatory scheme, depicted on the 1988 USSR stamp. He was one of Islam's greatest astronomers during the Middle Ages.


Ulugh's scientific expertise was not matched by his skills in governance. He lost some battles to rival kingdoms, and, in 1448, he massacred the people of Herat after defeating Mirza Ala-u-dowleh, son of Bai Sunqur. Within two years, he was beheaded by his own eldest son, 'Abd al-Latif, while on his way to Mecca. Eventually, his reputation was rehabilitated by his relative, Babur, founder of the Mughal Empire, who placed Ulugh Beg's remains in the tomb of Timur in Samarkand, where they were found by archeologists in 1941.

The crater, Ulugh Beigh, on the Moon, was named for him by the German astronomer Johann Heinrich von Mädler on his 1830 map of the Moon.


  • Muslim scholars


  1. ^ B.F. Manz, "Tīmūr Lang", in Encyclopaedia of Islam, Online Edition, 2006
  2. ^ Tom Bissell, Chasing the Sea, Pantheon (2003). ISBN 0375421300. p. 193


  • O'Connor, John J.; Robertson, Edmund F., "Ulugh Beg", MacTutor History of Mathematics archive .
  • 1839. L. P. E. A. Sedillot (1808-1875). Tables astronomiques d’Oloug Beg, commentees et publiees avec le texte en regard, Tome I, 1 fascicule, Paris. A very rare work, but referenced in the Bibliographie generale de l’astronomie jusqu’en 1880, by J.
  • 1847. L. P. E. A. Sedillot (1808-1875). Prolegomenes des Tables astronomiques d’Oloug Beg, publiees avec Notes et Variantes, et precedes d’une Introduction. Paris: F. Didot.
  • 1853. L. P. E. A. Sedillot (1808-1875). Prolegomenes des Tables astronomiques d’Oloug Beg, traduction et commentaire. Paris.
  • Le Prince Savant annexe les étoiles, Frédérique Beaupertuis-Bressand, in Samarcande 1400-1500, La cité-oasis de Tamerlan : coeur d'un Empire et d'une Renaissance, book directed by Vincent Fourniau, éditions Autrement, 1995, ISSN 1157 - 4488.
  • L'âge d'or de l'astronomie ottomane, Antoine Gautier, in L'Astronomie, (Monthly magazine created by Camille Flammarion in 1882), December 2005, volume 119.
  • L'observatoire du prince Ulugh Beg, Antoine Gautier, in L'Astronomie, (Monthly magazine created by Camille Flammarion in 1882), October 2008, volume 122.
  • Le recueil de calendriers du prince timouride Ulug Beg (1394-1449), Antoine Gautier, in Le Bulletin, n° spécial Les calendriers, Institut National des Langues et Civilisations Orientales, juin 2007, pp. 117–123.
  • This article incorporates text from the Encyclopædia Britannica, Eleventh Edition, a publication now in the public domain.
  • Jean-Marie Thiébaud, Personnages marquants d'Asie centrale, du Turkestan et de l'Ouzbékistan, Paris, éditions L'Harmattan, 2004. ISBN 2-7475-7017-7.

External links

  • Wikimedia Commons logo Media related to Ulugh Beg at Wikimedia Commons
  •  "Ulugh Beg". Encyclopædia Britannica (11th ed.). 1911. 

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