Day 41: Ulugbek Observatory

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remains of the Ulugbek observatory, pinnacle of 15th century astronomy – photo credit Oleg Brovko wikipedia commons

Affairs of the state often kept Ulugbek from his passion for the stars, but being Sultan comes with its perks.  In addition to founding three madrassas to advance the world’s understanding of astronomy and mathematics, the Timurid ruler also built one of the most important observatories of the Middle Ages in his capital city of Samarkand.

The construction of an observatory was the realization of a lifelong dream for Ulugbek who had visited the Maragheh Observatory in Iran as a child.  This visit kindled his passion for lifelong learning and led him to eventually build his own.  In 1428 construction of the Ulugbek Observatory was completed, and work began immediately on what would become the greatest astronomical catalog since Almagest was compiled by the famous Greco-Roman astronomer Claudius Ptolemy in the 2nd century AD.

Ptolemy’s star catalog was the gold standard astronomical directory in the western and Arab world for over a thousand years.  Containing 1025 stars and nebulae, Almagest was used by the Persian astronomer Al-Sfui in the 10th century, and subsequently by Nasir ad-Din Tusi who founded the observatory which inspired Ulugbek as a child.

Together with the scientists Ulugbek brought from across the Islamic world, he compiled the Gurgan Zij, an astronomical table considered the most accurate since Ptolemy’s work more than a thousand years prior.  Ulugbek calculated the length of the sidereal year to 365 days, 5 hours, 49 minutes, and 15 seconds, which was even more accurate than the calculations of Copernicus 88 years later.

1024px-Ulugh_Beg's_Astronomic_Observatory
underground preserved portion of the sextant used to calculate the positions of over a thousand stars – photo credit Igor Pinigin, wikipedia commons

The primary feature of Ulugbek’s observatory was a wall quadrant (or sextant) with a radius of 40 meters, compared to the 28 meters of the Maragheh Observatory from which Ulugbek drew his inspiration.  With such an advanced scientific instrument, the program of observations at the observatory necessary to compile the Gurgan Zij took nearly 30 years, from 1420 to 1449.

Even after the murder of Ulugbek by his eldest son while on a trip to Mecca, the observatory continued to function for another 20 years. By 1469 the political situation in Smarkand had deteriorated to the point where most of the city’s scholars and scientists fled to Herat in modern day Afghanistan.  By the 16th century, the observatory had fallen into disuse, especially after the capital was moved to Bukhra under the Shaybanid dynasty.

Meanwhile in Europe, the renaissance was in full swing.  The Gurgan Zig star catalogue succeeded Ptolemy’s Almagest in accuracy but was only first published in Europe in the year 1650.  Unfortunately, around about this time the Ulugbek Observatory was reduced to bricks, its components used for building projects elsewhere in the city.  Soon the site was completely lost to the sands of time, its fate becoming one of the great archeological mysteries of the world.

The 1908 discovery of the remains of the observatory by Russian archeologist Vasily Lavrentievich is widely considered to be one of the great archeological finds of the 20th century.  Today all that remains is the underground portion of the original 40 meter sextant which is now housed under a protective covering with a decorative iwan for an entrance portal.

Today the site serves as a historical tourist attraction, where in addition to seeing the remnants of Ulugbek’s Observatory, travelers can also visit a museum about his contributions to the understanding of our place in this universe.

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