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IranHistory of Science

Meraga Observatory

Human nature is inherently curious and driven to explore. Perhaps one of the most intriguing subjects that have piqued human curiosity for centuries is the sky, which includes stars, planets, and celestial bodies—in short, astronomy. Scholars in Islamic civilization, just like in other fields of knowledge, made significant contributions to astronomy, reaching the highest levels of expertise. To conduct their astronomical research more comprehensively, these astronomers established observatories, which they called “rasathane.” One of the important observatories in Islamic civilization was the Meraga Observatory. In this article, we will explore the establishment of the Meraga Observatory, its research endeavors, and the scholars it hosted.


The Meraga Observatory was the first major, well-equipped observatory in terms of organization within Islamic civilization. It was established in the city of Meraga, located in the Iranian territories, by the Ilkhanate ruler Hulagu after the conquest of Baghdad. Nasir al-Din al-Tusi was appointed by Hulagu to establish the Meraga Observatory. Construction of the observatory began in 1259, and it was completed in 1270, five years after Hulagu’s death. The Meraga Observatory was exceptionally advanced for its time, both in terms of the quality of the scholars it housed and the fully equipped observational instruments it possessed.

Nasıreddin Tusi’nin çalışma ekibi Tansuknamme-i İlhani’de bulunan bir minyatürde

When examining the structures built for observations at the Meraga Observatory, we find eastern-western and northern-southern walls, the central tower of the observatory, a library, a conference hall, a workshop, and a central structure with an eyvan (a traditional architectural element). A sextant was placed inside the central tower to determine the latitude and longitude of a location on Earth’s surface. Adjacent to the central tower were accommodations for the astronomers conducting astronomy work. Now, let’s delve into the identities of the scholars who conducted research at this observatory.

Scholars Educated at the Observatory

Nasir al-Din al-Tusi, the scholar who played a leading role in establishing the Meraga Observatory, also served as its director. Alongside him, around fifteen astronomers and mathematicians were involved in research at this observatory. Some of the notable scholars who worked at the Meraga Observatory included Kutb al-Din al-Shirazi, Fakhr al-Din al-Ahlati, Shams al-Din al-Amuli, Mu’ayyad al-Din al-Urdi, Ali ibn Umar al-Qazvini, Abu al-Shukr al-Maghribi, and Asir al-Din al-Abhari.

Observational Instruments at the Observatory

Most of the instruments used for observations at the Meraga Observatory were designed and built by Mu’ayyad al-Din al-Urdi and his son Muhammad. Unfortunately, only one celestial sphere, crafted by Muhammad, remains of the instruments produced during their time. The detailed descriptions of the instruments used at the Meraga Observatory in al-Urdi’s work are crucial for reconstructing these instruments.

Meraga Rasathanesi’nde astronomik ölçümler için kullanılan el-Urdi’nin tasarladığı Çemberli Küre

When we examine the instruments used at the observatory, we find that they included the double dial instrument, the double-arm instrument, and the perfect instrument, all designed and used by al-Urdi. In addition to these, the observatory housed instruments such as the ring dial, the solstitial ring, the wall quadrant, the equinoctial ring, and the celestial sphere, which were utilized for astronomical observation and measurement. The wall quadrant was used to determine the sun’s height and the ecliptic inclination. The double dial instrument was used to find the heights of stars, while the double-arm instrument aided in measuring the altitudes of celestial objects.

A Pioneering Institution

The research and instruments developed at the Meraga Observatory revolutionized the field of astronomy and served as an inspiration to astronomers and scholars far beyond Islamic civilization. Notably, Tycho Brahe, a prominent figure in the 16th century who established an observatory on the island of Hven, drew inspiration from the instruments found at the Meraga Observatory. The fact that the astronomical instruments used at the Meraga Observatory in the 13th century were on par with those used in European observatories in the 16th and 17th centuries is significant.

Research Conducted at the Observatory

El-Urdi’nin Aletler kitabındaki Duvar Kadranı çizimi

The primary purpose of the Meraga Observatory was to conduct new observations and prepare tables based on these observations. Astronomical observation and calculation activities continued over the years, culminating in the creation of the “Zij-i Ilkhani” in 1271. The “Zij-i Ilkhani” became the fundamental reference and handbook for astronomers. It featured studies on different calendars and provided the coordinates of certain stars and 256 cities.

The Meraga Observatory was active until 1339 and hosted significant research activities. Besides its role as an astronomical observatory, it also served as an educational institution where various subjects, including mathematics and astronomy, were taught. Inside the observatory, there was a library containing approximately four hundred thousand books collected from Syria, Iraq, and Iran. The Meraga Observatory was not limited to providing education exclusively to Muslim students; it also welcomed foreign or non-Muslim students interested in studying astronomy. Nasir al-Din al-Tusi ensured financial support for those conducting scientific research at the observatory, which encouraged scientific endeavors.

A Leading Figure at the Observatory: Nasir al-Din al-Tusi


Nasir al-Din al-Tusi, who was instrumental in the establishment of the Meraga Observatory, was a prolific scholar with contributions in various fields, including astronomy. He was born in Tus in 1201 and received his initial education from his father before traveling to various centers of learning to further his studies. Due to the political turmoil of the time, he moved between cities in search of a conducive environment for scholarly pursuits.

Eventually, he found patronage under the Mongol ruler Hulagu, who entrusted him with the administration of several institutions, including the Meraga Observatory. Tusi passed away in 1274. He made significant contributions in fields such as astronomy, mathematics, theology, philosophy, logic, ethics, and psychology. One of his notable achievements was differentiating astronomy from trigonometry and considering it as a branch of mathematics. He also made significant contributions to algebra and mathematics literature.

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