Ulugh Beg Observatory

The Ulugh Beg Observatory is an observatory in Samarkand, Uzbekistan. Built in the 1420s by the Timurid astronomer Ulugh Beg, it is considered by scholars to have been one of the finest observatories in the Islamic world. Some of the famous Islamic astronomers who worked at the observatory include Al-Kashi, Ali Qushji, and Ulugh Beg himself. The observatory was destroyed in 1449 and rediscovered in 1908.

In 1420, the great astronomer Ulugh Beg built a madrasah in Samarkand, named the Ulugh Beg Madrasah. It became an important center for astronomical study and only invited scholars to study at the university whom he personally approved of and respected academically and at its peak had between 60 and 70 astronomers working there. In 1424, he began building the observatory to support the astronomical study at the madrasah and it was completed five years later in 1429. Beg assigned his assistant and scholar Ali Qushji to take charge of the Ulugh Beg Observatory which was called Samarkand Observatory at that time. He worked there till Ulugh Beg was assassinated. Other notable astronomers made observations of celestial movements at the observatory, including Qāḍīzāda al-Rūmī and Jamshid Kashani.

However, the observatory was destroyed by religious fanatics in 1449 and was only re-discovered in 1908, by a Uzbek-Russian archaeologist from Samarkand named V. L. Vyatkin, who discovered an endowment document that stated the observatory's exact location.

While working at the excavation site, Vyatkin found one of the most important astronomical instruments used at the observatory: a large arch that had been used to determine midday. A trench of about 2 metres wide was dug in a hill along the line of the Meridian and in it was placed the arc of the instrument. Today, there is a circular base showing the outline of the original structure and the doorway leads to the remaining underground section of the Fakhrī sextant that is now roofed over. The sextant was 11 metres long and once rose to the top of the surrounding 3 storey structure although it was kept underground to protect it from earthquakes. Calibrated along its length, it was the world's largest 90 degree quadrant at the time, with a radius of 40.4 metres. The radius of the meridian arc was according to a trusted middle age Turkish astronomer approximately 50 metres and was said to be the same height as the dome of the Hagia Sofia mosque in Istanbul. It was used for the observation of the Sun, Moon and other celestial bodies, and along with other sophisticated equipment such as an armillary and an astrolabe, the astronomers working in Samarkand could determine noon every day according to the meridional height of the Sun, distance from the zenith and declination.

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