Ulugh Beg

By Lucía Cárdenas

He was the grandson of Timur — Tamerlane, the lame conqueror who stacked skulls from Delhi to Damascus — and he chose the stars over the sword. Muhammad Taraghay, called Ulugh Beg, the Great Prince, was born in 1394 during one of his grandfather's campaigns and grew up in a court where power was measured in cities sacked. When he became governor, then effectively ruler, of Transoxiana, he built his capital at Samarkand into something his grandfather would not have recognized: a city of scholars.

Around 1420 he began the work that defines him. On a hill outside Samarkand rose an observatory unlike anything since Maragha — dominated by a gigantic meridian arc, a sextant sunk into a trench eleven meters deep and forty meters long, aligned with the meridian to measure the sun and stars to fractions of a degree. Around it gathered the finest astronomers of the age: Qadi Zada al-Rumi, Jamshid al-Kashi — who died as the work began — and Ali Qushji, who would carry the school's legacy to Istanbul. For nearly two decades they measured the sky, night after night, star after star.

The result, published around 1437, was the Zij-i Sultani — the Sultanic Tables — a star catalog of 1,018 stars with positions determined to a precision no one would surpass until Tycho Brahe, a century and a half later, working with better instruments in Denmark. Ulugh Beg's value for the length of the year, 365 days 6 hours 10 minutes 8 seconds, missed the truth by 58 seconds. His tables of planetary motion remained the best in the world until the telescope age.

Then came the other half of his life, the half that killed him. Drawn into the Timurid succession struggles after his father Shah Rukh's death, he marched against his own rebellious son, Abd al-Latif. Defeated and captured in 1449, he was murdered — by some accounts on his son's orders, while on pilgrimage to Mecca. The observatory was sacked by religious zealots; the great arc was buried. Ali Qushji fled west with a manuscript of the tables. It reached Istanbul, then Europe, where Johannes Hevelius would publish it in Latin in 1665 as the first star catalog of the Islamic world to enter Western astronomy. The prince who measured the heavens was killed by the earthbound politics he never mastered — but the stars he fixed are still where he left them.

Impact on civilization

Ulugh Beg's Zij-i Sultani was the most accurate star catalog in human history until Tycho Brahe, setting a standard of observational precision that stood for 150 years. His Samarkand observatory — with its monumental meridian arc and international staff — proved that systematic, long-baseline observation could outdo the theoretical brilliance of any single astronomer, a lesson institutionalized in every later national observatory. His tables fed Ottoman, Indian, and eventually European astronomy, forming a bridge between the Maragha school and the Renaissance. He showed that a ruler's greatest conquest could be a dataset.