Lo! some we loved, the loveliest and best
That Time and Fate of all their Vintage prest,
Have drunk their Cup a Round or two before,
And one by one crept silently to Rest.

Mirzo Ulugbek

Ulugh Beg (Persian: میرزا محمد طارق بن شاہرخ الغ‌بیگ‎ – Mīrzā Muhammad Tāraghay bin Shāhrukh Uluġ Beg) (March 22, 1394 in Sultaniyeh (Persia) – October 27, 1449 (Samarkand)) 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. His real name was Mīrzā Mohammad Tāraghay bin Shāhrokh. Ulugh 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 build the Ulugh Beg Madrasah (1417–1420) in Samarkand and Bukhara, transforming the cities into 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.


Early life

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 inSultaniyeh 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 the Shah Ruks'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 (currently in Uzbekistan), and he invited numerous Islamic astronomers and mathematicians to study there. The madrasa building still survives. Ulugh Beg's most famous pupil in astronomy wasAli Qushchi (died in 1474).

Ulugh Beg 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 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 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 first edited by Thomas Hyde at Oxford in 1665 under the title Tabulae longitudinis et latitudinis stellarum fixarum ex observatione 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 inUlugh Beg's Catalogue of Stars, Revised from all Persian Manuscripts Existing in Great Britain, with a Vocabulary of Persian and Arabic Words(1917).

Ulugh Beg and his astronomical observatory scheme, depicted on the 1987USSR stamp. He was one of Islam's greatest astronomers during the Middle Ages. The stamp says "Uzbek astronomer and mathematician Ulugbek" in Russian.

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 as 365d 5h 49m15s, 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.[6]


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


Ulugh's scientific expertise was not matched by his skills in governance. When he heard of the death of his father Shah Rukh, Ulugh Beg went to Balkh, where he heard that his Mirza Ala-ud-Daulah, 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 Morgab. 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 'Abd al-Latif, 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 relative, 'Abdullah (1450–1451), 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 after him by the German astronomer Johann Heinrich von Mädler on his 1830 map of the Moon.