Ulugh Beg's Samarkand Observatory and the Zij-i Sultani Star Catalogue
- Date
- c. 1428 (observatory); Zij-i Sultani completed 1438-1439
- Category
- Science, technology & invention
- Region
- Central Asia (Samarkand, Transoxiana, modern Uzbekistan)
- Era
- Post-Classical / Medieval
- Significance
Around 1428, the Timurid ruler and astronomer Ulugh Beg, grandson of Timur (Tamerlane), completed a monumental observatory at Samarkand in Transoxiana (modern Uzbekistan).
Its centerpiece was the Fakhri sextant, a meridian arc with a radius of roughly 40 metres built into a trench aligned to the meridian, the largest astronomical instrument of its era and capable of measurements of remarkable precision. Working with leading scholars including Jamshid al-Kashi, Qadi Zada al-Rumi, and Ali Qushji, Ulugh Beg produced the Zij-i Sultani (completed c. 1437-1439), a star catalogue and set of astronomical tables listing 992 stars determined from fresh observation rather than merely updating Ptolemy. The work yielded strikingly accurate values for the length of the year and the tilt of Earth's axis, and it remained the most precise such catalogue in the world until the observations of Taqi ad-Din and Tycho Brahe in the late 16th century. The observatory marked the high point of medieval Islamic astronomy and was destroyed soon after Ulugh Beg's assassination in 1449, its foundations rediscovered only in 1908.
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Empires active in c. 1428 (observatory); Zij-i Sultani completed 1438-1439
- Malacca Sultanate1400 CE – 1511 CE
- Aztec Empire1428 CE – 1521 CE
- Ming Dynasty1368 CE – 1644 CE
- Kanem-Bornu Empire700 CE – 1900 CE
- Ottoman Empire1299 CE – 1922 CE
- Solomonic dynasty1270 CE – 1974 CE
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- Madhava and the Kerala School develop infinite seriesc. 1400
- Jikji printed in Korea, oldest extant book made with movable metal typeJuly 1377
- Ibn al-Nafis Describes the Pulmonary Circulation of the Bloodc. 1242 CE
- Al-Jazari Completes the Book of Knowledge of Ingenious Mechanical Devices1206 CE
Further reading
The wider story
A Little History of Science
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