Ulugh Beg

Ulugh Beg mirzo - ruler, astronomer, mathematician, and sultan

Mirza Muhammad Taraghay bin Shahrukh more known as Ulugh Beg, was born on March 22, 1394, in Sultaniyeh (Persia) – died on October 27, 1449, in SamarkandUlugh Beg was also notable for his work in astronomy-related mathematics, such as trigonometry and spherical geometry. He built the great Ulugh Beg Observatory in Samarkand between 1424 and 1429. It was considered by scholars to have been one of the finest observatories in the Islamic world at the time and the largest in Central Asia. He also builds the Ulugh Beg Madrasah (1417–1420) in Samarkand and Bukhara, transforming the cities into the cultural center of learning in Central Asia. He was also a mathematics genius of the 15th century — albeit his mental aptitude was perseverance rather than any unusual endowment of intellect. He ruled Uzbekistan, Tajikistan, Turkmenistan, Kyrgyzstan, and southern Kazakhstan for almost half a century from 1411 to 1449 and occupied the Herat province in Afghanistan for a short time in 1448.


He was a grandson of the great conqueror, Timur (Tamerlane) (1336–1405), and the oldest son of Shah Rukh, both of whom came from the Turkicized Barlas tribe of Transoxiana (now Uzbekistan). His mother was a Persian noblewoman named Goharshad. Ulugh Beg was born in Sultaniyeh in Persia during Timur’s invasion. As a child, he wandered through a substantial part of the Middle East and India as his grandfather expanded his conquests in those areas. After Timur’s death, however, and the accession of Ulugh Beg’s father too 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 his governor in Samarkand in 1409. In 1411, he became the sovereign ruler of the whole Mavarannahr khanate.

Science. Astronomy, Mathematics

The teenage 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 astronomy was Ali Qushchi, who died in 1474.

Ulug Beg’s particular interests focused 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 Istanbul. 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 catalog 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 catalogs, 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 catalog Book of Fixed Stars from the year 964, which were too far south for observation from Samarkand. This catalog, one of the most original of the Middle Ages, was first edited by Thomas Hyde at Oxford in 1665 under the title Tabulae longitudinal et latitudinal stellarum fixarum ex observation Ulugbeighi and reprinted in 1767 by G. Sharpe. More recent editions are those by Francis Baily in 1843 in vol. xiii of the Memoirs of the Royal Astronomical Society and by Edward Ball Knobel in Ulugh Beg’s Catalogue of Stars, Revised from all Persian Manuscripts Existing in Great Britain, with a Vocabulary of Persian and Arabic Words (1917).

In 1437, Ulugh Beg determined the length of the sidereal year as 365.2570370…d = 365d 6h 10m 8s (an error of +58 seconds). In his measurements, within many years he used a 50 m high gnomon. This value was improved by 28 seconds in 1525 by Nicolaus Copernicus, who appealed to the estimation of Thabit ibn Qurra (826–901), which had an error of +2 seconds. However, Beg later measured another more precise value 365d 5h 49m 15s, which has an error of +25 seconds, making it more accurate than Copernicus’ estimate which had an error of +30 seconds. Beg also determined the Earth’s axial tilt as 23.52 degrees, which remained the most accurate measurement for hundreds of years. It was more accurate than later measurements by Copernicus and Tycho Brahe.

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


Ulugh Beg’s scientific expertise was not matched by his skills in governance. When he heard of the death of his father Shahrukh Mirza, Ulugh Beg went to Balkh, where he heard that his nephew Ala-ud-Daulah Mirza bin Baysonqor, son of Ulugh’s brother Baysonqor, had claimed the emirship of the Timurid Empire in Herat. Consequently, Ulugh Beg marched against Ala-ud-Daulah and met him in battle at Murghab. Having won this battle, Ulugh Beg advanced toward Herat and massacred its people in 1448, but Ala-ud-Daulah’s brother Mirza Abul-Qasim Babur bin Baysonqor came to his aid, defeating Ulugh Beg. Ulugh Beg retreated to Balkh, where he found that its governor, his oldest son Abdal-Latif Mirza, had rebelled against him. Another civil war ensued. Within two years, he was beheaded by the order of his own eldest son while on his way to Mecca. Eventually, his reputation was rehabilitated by his nephew, Abdallah Mirza (1450–1451), who placed Ulugh Beg’s remains in the mausoleum of Timur in Samarkand, where they were found by archeologists in 1941. The crater, Ulugh Beigh, on the Moon, was named after him by the German astronomer Johann Heinrich von Madler on his 1830 map of the Moon.

Observatory and Memorial Museum of Mirzo Ulugbeg

Memorial Museum of Ulugbek has been set next to the ruins of his observatory. The museum has a collection of documentation relating to Ulugbeg heritage. 

The museum staff has recreated the environment in which he lived and worked. Various miniatures by Uzbek artists depict the scenes where Ulugbek is engaged in public affairs with his colleagues and communicates with his students. The museum’s collection also includes articles and books of Ulugbek’s period which allows seeing the full significance of his heritage.

Ulugh Beg, was a Timurid sultan, astronomer and mathematician.

Ulugbek made a huge contribution to the development of astronomy. He explaining the foundations of this science and indicated the coordinates of more than 1000 stars. The construction of his observatory started in 1424 on the Kuhak hill and in five years later it was equipped with a goniometer with a radius of 40.21 m. The building itself was three-story and had a height of 30.4 m. 

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