Ulugh Beg Builds the Samarkand Observatory
A Timurid prince recruits sixty scientists and produces a star catalog of nearly a thousand stars
Quick facts
- Builder
- Ulugh Beg, grandson of Timur
- Construction began
- 1428 CE
- Star catalog
- Zij-i Sultani, published 1437, 992 stars
- Key collaborators
- Al-Kashi, Qadi Zada
What happened
Ulugh Beg, grandson of Timur and ruler of the Timurid realm centered on Samarkand, built a major astronomical observatory there, with construction beginning in 1428. The observatory was circular in shape, had three levels, and measured over 50 metres in diameter and 35 metres high, designed to house enormous fixed astronomical instruments for precise measurement. Ulugh Beg invited roughly sixty scientists to work at his adjoining madrasah and observatory, including the astronomer and mathematician al-Kashi and the scholar Qadi Zada, and he personally led scientific meetings where astronomical problems were freely discussed among the staff. The combined effort of Ulugh Beg, al-Kashi, and Qadi Zada produced the Zij-i Sultani, a star catalog published in 1437 giving the positions of 992 stars. The observatory itself survived the Uzbek conquest of Samarkand in 1500 before eventually falling into ruin.
Why it matters
The Samarkand Observatory was, for its time, the best-equipped astronomical institution anywhere, and its star catalog updated and improved on Ptolemy's and al-Battani's positional data with new naked-eye observations made using purpose-built, large-scale instruments. It stands as one of the last great achievements of pre-telescopic Islamic observational astronomy before European astronomy, aided by the telescope, would overtake it within two centuries.
How we know
The Samarkand Observatory's construction, dimensions, and staff are documented in contemporary and near-contemporary Islamic biographical and scientific writing, and the Zij-i Sultani star catalog itself survives, letting historians verify its 992 recorded star positions directly against the original text.
Sources
- MacTutor History of Mathematics, University of St Andrews. Ulugh Beg · Reputable sourcemathshistory.st-andrews.ac.uk · The domain "mathshistory.st-andrews.ac.uk" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- MacTutor History of Mathematics, University of St Andrews. The Samarkand Observatory · Reputable sourcemathshistory.st-andrews.ac.uk · The domain "mathshistory.st-andrews.ac.uk" is on our Reputable source registry.
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