The Star-Gazing Sultan and His Ulugh Beg Observatory

The Ulugh Beg Observatory is an astronomical observatory located on a hill near Samarkand, in modern day Uzbekistan. This observatory, which is often considered to be one of the finest of its kind in the medieval Islamic world, was constructed during the 15th century when Samarkand was one of the two most important cities of the mighty Timurid Empire (the other being Herat, in modern day Afghanistan).

The observatory was built by Ulugh Beg, sultan of the Timurid Empire. The Ulugh Beg Observatory is believed to have been built during the late 1420s, though serious studies in astronomy may have already begun in Samarkand two decades beforehand. This is entirely possible, as Ulugh Beg was governor of Samarkand at that time.

Ulugh Beg: The Rising Astronomer

Ulugh Beg was interested in astronomy from an early age, and when he became sultan he continued to be far more interested in the arts, culture and scholarly pursuits than in governing an empire. In fact, Ulugh Beg is best remembered as an astronomer and mathematician. Otherwise, his name would have likely been relegated to a mere footnote in the history books.

Statue of Ulugh Beg (CC BY-SA 3.0­­­)

Ulugh Beg was born in 1394 in Sultaniyah, northwestern Iran. He was the eldest son of Shah Rukh, and a grandson of Timur (known also as Tamerlane), the founder of the Timurid Empire. Ulugh Beg was born during his grandfather’s Persian campaign, and was given the name Muhammad Taraghay ibn Shahrukh ibn Timur. Incidentally, “Ulugh Beg” may be roughly translated as “Great Ruler”. This was the Timurid sultan’s nickname, rather than personal name.

As a child, Ulugh Beg accompanied his grandfather on his various military campaigns, giving him the chance to travel widely. In 1398, for instance, Timur was on a campaign in northern India, capturing the city of Delhi, whilst in 1402, he was in Anatolia, defeating the Ottoman sultan, Bayezid I, at the Battle of Ankara.

Ulugbek Medressa. (Arian Zwegers / CC BY 2.0)

Since his childhood, Ulugh Beg took a greater interest in the arts and culture, rather than in wars and conquests. He was particularly passionate about astronomy, an interest which may have originated from a visit to the ruins of the Maragheh Observatory. This observatory, which dates to the 13th century, is located in northwestern Iran, not too far from Ulugh Beg’s birthplace. The Maragheh Observatory was built under the patronage of Hulagu Khan, the founder of the Ilkhanate, and a grandson of Genghis Khan. The head astronomer of the observatory was the Persian polymath Nasir al-Din Tusi.

The Maragheh Observatory fell into disuse by the beginning of the 14 ^th century as a result of its loss of patronage. It did however maintain its fame for centuries to come, and the fact that its plan and arrangement of instruments influenced the design of future observatories, such as the Ulugh Beg Observatory, is testament to its legacy.

Painting of Al-Tusi and his colleagues working on the Zij-i Ilkhani at the Maragheh observatory. (Public domain)

Game of Thrones: How Ulugh Beg Became Sultan

Timur’s dream was to restore the Mongol Empire, which included the invasion and conquest of China. The Mongols, under the Yuan Dynasty, had been ruling China until 1368. In that year, the Mongols lost their grip on China and were replaced by the Ming Dynasty. Therefore, in late 1404, Timur was preparing to invade China. The sultan’s dream to restore the Mongol Empire, however, never materialized, and he died in the following year.

Whilst encamped on the side of the Syr Darya (known also as the Jaxartes River), Timur’s army was struck by a plague. Timur himself fell ill, and died mid-February at Otrar (in modern day Kazakhstan), still a long way off from China’s western borders. As a consequence of Timur’s death, the empire fragmented, as Timur’s descendants fought for his throne. Amongst the main contenders were Miran Shah and Shah Rukh (the two surviving sons of Timur), Pir Muhammad (the son of Jahangir who was Timur’s favorite son and designated heir), and Khalil Sultan (Miran Shah’s son).

All of these claimants to the Timurid throne, with the exception of Shah Rukh, were dead by 1410. Although Shah Rukh was not considered to be the strongest candidate, he was the one who eventually emerged victorious. Between 1406 and 1417, Shah Rukh absorbed the territories of his rivals, and succeeded in reuniting the Timurid Empire, save for Syria and Khuzistan. Shah Rukh ruled the Timurid Empire until his death in 1447. His long reign was a period of economic prosperity, and much of the damage caused by his father’s campaign was repaired.

Samarkand: Center for Science in the Medieval Islamic World

Shah Rukh moved the capital of the Timurid Empire from Samarkand to Herat. The old capital, which he captured from one of his rivals, was given to Ulugh Beg to govern. Under Ulugh Beg’s rule, Samarkand was transformed into one of the most important centers of learning in the Islamic world. The Ulugh Beg Madrasa, located at the heart of the city (known as the Registan, meaning “sandy place”) was built between 1417 and 1420.

The public square in Registan, in the heart of the ancient city of Samarkand, is surrounded by three madrasas (Islamic schools), one of which is the Ulugh Beg Madrasah built by Ulugh Beg during the Timurid dynasty. (Ekrem Canli / CC BY-SA)

The madrasa was a school that imparted both religious and secular knowledge to its students. In addition, it was also a meeting place for scholars. According to Ghiyath al-Din Jamshid al-Kashi, the 14 ^th to 15 ^th century Persian astronomer, there were about sixty or seventy scholars at the madrasa who had sufficient knowledge in mathematics to take part in astronomical observations and seminars. Ulugh Beg founded two other madrasas during his reign, one in Bukhara, and another in Ghujdivan.

Interior courtyard at the Ulugh Beg Madrasa (Public domain)

Construction of the Ulugh Beg Observatory is believed to have begun in 1428, based on the design of the Maragheh Observatory. Although much of the Ulugh Beg Observatory has not survived, the monument has been reconstructed based on the descriptions provided by those who saw the observatory or its remains. These include the writings of Ghiyath al-Din Jamshid al-Kashi, Babur, the founder of the Mughal Empire, and Abd al-Razzak Samarkandi, a 15 ^th century historian.

The Maragheh Observatory served as a model not only for the Ulugh Beg Observatory, but also for other observatories in the Islamic world. These observatories provided further information regarding the design of the Ulugh Beg Observatory. On top of that, archaeological excavations of the site have made the reconstruction of the Ulugh Beg Observatory possible.

Ulugh Beg Observatory and Its Contributions to Islamic Astronomy

During its heyday, the building would have consisted of three gigantic astronomical instruments. The most important of the three was the suds-i fakhri, a colossal meridian arc or sextant that ran through the observatory’s center. The instrument was placed on a north-south axis, and would have reached a height of 40 m (131 ft.). The second instrument was the I’tidal, or solar clock, made up of a wall with a concave profile. The instrument was built on an east-west axis, perpendicular to the suds-i Fakhri. By this means, the sextant functioned as the clock’s gnomon. The third instrument was the ustuvan, which was a rotating quadrant sector.

Entrance of the Ulugh Beg Observatory in Samarkand, Uzbekistan, famed as one of the pre-eminent observatories in the Islamic world. (robnaw/ Adobe Stock)

The positioning of these instruments contributed to the structure and layout of the Ulugh Beg Observatory. For instance, the suds-i fakhri divided the observatory into two halves – a northern one, and a southern one. The rooms located at the northern half were cruciform in plan, whereas those in the southern half were rectangular. From the descriptions of the Ulugh Beg Observatory, researchers have learned that the building was decorated with glazed brick mosaics, and that both the interior and exterior of the structure were covered in paintings depicting the position, orbit, and physical characteristics of the heavenly bodies.

Arguably the most important piece of work to be produced by the Ulugh Beg Observatory was the Zij-I Sultani, which was published in 1437. According to the Encyclopaedia Britannica, a zij is essentially a “handbook of astronomical tables, including tables for working out positions of the Sun, Moon, and planets, accompanied by directions for using them.” At the time of its publication, Ulugh Beg’s zij was the most accurate of its kind. In addition, this work was notable for its “updated values for astronomical parameters and new computational procedures,” explains the UNESCO Portal to the Heritage of Astronomy. Moreover, this work recorded the positions of approximately 1018 stars, some of which are original, as they were determined from observations made at the Ulugh Beg Observatory.

When visiting the Ulugh Beg Observatory, visitors can view the lower section of the meridian arc which helped astronomers of the time accurately measure the planets and the stars. (demerzel21 / Adobe Stock)

Unfortunately for Ulugh Beg and his astronomers, their work did not have the impact on “modern” astronomy that it should have had. The data produced at the Ulugh Beg Observatory only made its way to Europe several centuries after the sultan’s death. By that time, other astronomers had already replicated their findings.

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The Tragic Fate of the Sultan Astronomer 

Ulugh Beg himself suffered a tragic fate. When Shah Rukh died in 1447, Ulugh Beg became the new ruler of the Timurid Empire. Although Ulugh Beg was a capable scholar, he seems to have lacked the skills needed to run an empire. Although he was his father’s only surviving son, there were other members of the Timurid royal family who coveted the throne for themselves. Therefore, Ulugh Beg’s first task as sultan would have been to consolidate his position. He failed to do so, probably due to a lack of leadership skills. Ulugh Beg fought against his rivals for full control of the Timurid Empire, but was not entirely successful in this undertaking.

Statue of Ulugh Beg in Samarkand, Uzbekistan. (Public domain)

Ulugh Beg’s reign came to an abrupt end after two years. By 1449, the sultan had been defeated in several battles. Moreover, in that year, he had to deal with a fresh revolt. ‘Abd al-Latif, Ulugh Beg’s eldest son, had been given the governorship of Balkh, but had a falling out with his father. As a result, ‘Abd al-Latif launched a revolt in 1449. Ulugh Beg was defeated by his son, and surrendered to him. ‘Abd al-Latif put his father on trial, and found him guilty of ineptitude. As punishment, Ulugh Beg was forced to make a pilgrimage to Mecca, but just outside Samarkand the sultan was beheaded by assassins. As they were most likely hired by his son, ‘Abd al-Latif was given the byname ‘Padarkush’, which means ‘killer of his father’. Following Ulugh Beg’s death, the Timurid Empire was spilt in two.

Like the Maragheh Observatory, the loss of patronage spelled the end for the Ulugh Beg Observatory. The observatory was destroyed, and the astronomers who worked there were sent away. The Ulugh Beg Observatory gradually fell into obscurity, and in time, even its exact location was forgotten. In 1908, the site of the Ulugh Beg Observatory was rediscovered by the Russian archaeologist Vassily Vyatkin. By this time, all that remained were its foundations and bits of the suds-i Fakhri (more specifically, the underground part of the instrument). Incidentally, Vyatkin is buried at the site, according to his wishes. Another major excavation, led by the Soviet archaeologist Boris Zasypkin, was conducted at the site in 1941. The excavation allowed hypothetical reconstructions of the observatory to be made.  

The Islamic astronomer and sultan Ulugh Beg on a 1987 USSR stamp (Mariluna / Public domain)

The Legacy of Ulugh Beg

Ulugh Beg may not have lived up to the nickname given to him, but he is considered a national hero in Uzbekistan today. Needless to say, this is due to his contributions to and achievements in the field of astronomy and mathematics. In 1970, a small museum was built on the site of the Ulugh Beg Museum, in commemoration of its founder. Amongst the objects displayed in the museum are copies of Ulugh Beg’s star charts and the Zij-I Sultani, a miniature reconstruction of the Ulugh Beg Observatory, and astronomical instruments.

Recognition for Ulugh Beg as an astronomer is evident in the naming of astronomical objects and features after him. For instance, the German astronomer Johann Heinrich von Mädler, named a on the moon after the star-gazing sultan, the Ulugh Beigh Crater, and included it on his 1830 map of the moon. In more recent times, Ulugh Beg lent his name to an asteroid. On the 21 ^st of August 1977, the Soviet astronomer Nikolai Chernykh discovered a main-belt asteroid and named it 2439 Ulugbek. Despite the destruction of his observatory, Ulugh Beg’s legacy lives on today.   

Satellite images of the Ulugh Beigh crate on the moon. (NASA / LRO_LROC_TEAM / Public domain)

Top image: Painting of astronomers located at the Ulugh Beg Observatory in Samarkand, Uzbekistan. Source: LoggaWiggler / CC0

By Wu Mingren