Maragheh observatory (Persian: رصدخانه مراغه), was an institutionalized astronomical observatory which was established in 1259 CE under the patronage of the Ilkhanid Hulagu and the directorship of Nasir al-Din al-Tusi, a Persian scientist and astronomer. Located in the heights west of Maragheh, which is today situated in the East Azerbaijan Province of Iran, it was once considered "the most advanced scientific institution in the Eurasian world".
It was financed by waqf revenues, which allowed it to continue to operate even after the death of its founder and was active for more than 50 years. The observatory served as a model for later observatories including the 15th-century Ulugh Beg Observatory in Samarkand, the 16th-century Taqi al-Din observatory in Constantinople, and the 18th-century Jai Singh observatory in Jaipur.
There were multiple buildings constructed at the observatory site including a main building, five other circular buildings containing observational instruments for astronomical research. Living quarters were also present on the site as well as a building for metal working. There was also a 330m^2 building that was used as the library. It is said that at one time the library held over 400,000 volumes of literature related to astronomy and astrology.
The main building is circular with a diameter of 22m. The entrance was 1.5m wide and opened to a hallway that was 3.1m wide that marked the meridian line. There were six rooms on either side of the hallway. These structures were made of mainly clay, brick, and mud. The final structure at the observatory was a tower. In a 340x135 m citadel-like area stood a four-story circular stone building with a diameter of 28m.
The mural quadrant to observe the positions of the stars and planets was aligned with the meridian. This meridian served as prime meridian for the tables in the Zij-i Ilkhani, as we nowadays apply the meridian which passes the Royal Greenwich Observatory for our astronomical calculations. In total the observatory spans an area that is 150 meters wide and 350 meters long. Today considerable parts of the groundwork from these structures are preserved in the ruins.
The construction of the observatory began in 1259. This is according to multiple books including Jam-e-ttavarikhe rashidi (Persian: جامع التواريخ رشيدي), saf-e-elhofreh (Persian: صاف الحفره), favat-o-lvafiyyat (Persian: فوات الوفيات)  The observatory came to be because of Nasir al-Din al-Tusi, a Persian mathematician, astronomer and philosopher who was well known around the world. He acted as an advisor to Hulagu, grandchild of Genghis Khan. Tusi complained to Hulagu that his astronomical tables had to be adapted to the latitude and longitude of Hulagu's new capital. Hulagu gave Tusi permission to build a new observatory in the location of his choosing, and Tusi chose Maragha, Iran where he became the director of the observatory. Men of mathematics, science, and astronomy came to the Maragheh Observatory from across the Islamic world and further. According to historical texts recovered from the observatory, the site had a reputation so widespread it had reached as far as China as students had traveled to study mathematics, physics, and astronomy. Other scholars in attendance included Bar-Hebraeus, who late in his life took residence close to the observatory in order to use the library for his studies. He has left a description of the observatory.
A number of other prominent astronomers worked with Tusi at the observatory, such as Muhyi al-Din al-Maghribi, Mu'ayyid al-Din al-'Urdi, from Damascus, Qutb al-Din al-Shirazi, and Hulagu's Chinese astronomer Fao Munji whose Chinese astronomical experience brought improvements to Ptolemaic system used by Tusi.
And after 12 years of intense work by Khaje Nassir od-Din Tussi and the other prominent scientists including Mu’yed al-Din al-Arad-Najmedin Cathy, Najmd al-Din Qazvini, Allame Qutbuddin Shirazi, and Fakhruddin Maraghi were compiled in the Zij-i Ilkhani, which later may have influenced the work of Copernicus. The tables were published during the reign of Abaqa Khan, Hulagu's son, was named after the patron of the observatory.
The downturn of the Maragheh Observatory began in the 13th century. After the death of Tusi in 1274 his son took over as director. However with the death of Hulagu in 1265 and his son Abaqa in 1282 the observatory no longer had patrons to fund the research being conducted. The observatory became inactive by the beginning of the 14th century. Over time the site turned to ruins as a result of frequent earthquakes and a lack of funding by the state to preserve the site. Shah Abbas the Great arranged for repair, however, this was not commenced due to the king's early death.
During the Mongol invasions and conquests in this region, the contents of the observatory's library were stolen.
A celestial globe from the observatory made around 1279 is now preserved in Dresden, Germany. It is a rare example of decorative art from Iran of the 13th century, designed by al-Urdi and made of bronze, inlaid with silver and gold.
Hulagu Khan: Patron of the ObservatoryEdit
Hulagu Khan was a Mongol ruler and the grandson of Genghis Khan. As the Mongols spread their territory Hulagu was put it charge of conquering Mesopotamia, Persia, Egypt, Syria, and the Abbasid Caliphate. From 1253 to 1256, Hulagu and his army were fighting to take control of the region of Iran known as Alamut. It was in 1256 that Hulagu took down the Castle of Alamut. Here he met al-Tusi. Many of the scholars of the region had fled to the mountains for sanctuaries to continue their studies as Tusi had in this Castle. However there is dispute over whether or not Tusi was there against his will, or even somehow helped the Mongols get in and attack.
Tusi was respected by Hulagu for his scholarship in science and decided to make him an advisor. Hulagu and his men, along with Tusi, then set course to Baghdad where the city was laid to waste. Hulagu later made Tusi a wazir, or a high ranking advisor or official. He also placed him in charge of waqf’s, or religious endowments. Given his trust in Tusi and his respect for the sciences and astronomy it is not surprising that Hulagu supplied the funding for the Maragheh Observatory when Tusi complained of needing new astronomy tables. He even made Maragheh the capital of his empire.
The observatory is currently covered with a dome-framed brass structure and is situated two miles west of Maragheh.
To save the installation from further destruction, the Cultural Heritage Organization of Iran built a dome-framed shelter and it plans to hold an exhibit of astronomical devices used at Maragheh Observatory.
Today the site is home to occasional star parties and though there are no official tours offered, the public is still welcome to come and see the remains of the observatory.
Astronomers Who Worked at the ObservatoryEdit
Nasir al-Din al-TusiEdit
Nasir Al-Din al-Tusi's most notable work was the creation of the Tusi-couple, a geometry based system that solved some of the fundamental issues with the Ptolemaic system’s description of planetary motion. The Tusi-couple uses two different sized circles with the smaller of the two placed with its center tangent to the larger circle. When a point is placed on the smaller sphere and both are set into motion, both rotating at different speeds with the smaller circle's center rotating with the larger circle, the point look's as if it was oscillating about a line. Some other notable works Tusi conducted were commentaries and revisions of Euclid's Elements and Ptolemy's Almagest as well as the astronomical handbook titled Zīj-i Īlkhānī detailing the movement of the planets, of which he was the lead author. 
Muhyi al-Dīn al-MaghribīEdit
Muhyi al-Dīn al-Maghribī was an astronomer who worked with Tusi at the observatory. His contributions in astronomy while working at the observatory are three comments in the Almagest relating the creation of an astrolabe, the determining of the meridian line and revolution of a sphere, and work on the Chinese and Uighur calendars.  Also while working at the observatory he wrote Khulāṣat al‐Majisṭī which translates to Summary of the Almagest. 
Mu'ayyid al-Din al-'UrdiEdit
Mu'ayyid al-Din al-'Urdi was an astronomer and engineer who was asked by Tusi to come to Marāgha and help design and construct the observatory. He played a key part in the building of the observatory by producing large water wheels to bring water towards the hill where the observatory would be. Al-'Urdi was noted as one of the instrument makers in the observatory and he wrote the treatise ‘Urḍī's Risāla fī Kayfiyyat al‐arṣād, which is preserved in a manuscript in Paris, and details the instruments in the observatory that were constructed before 1262 AD. Some notable instruments documented in this treatise include: the Mural quadrant, an armillary sphere which was used to measure the ecliptic longitude and latitude, a solstitial armilla which was used to determine the obliquity of the ecliptic, and equinoctial armilla which was used to determine when the sun entered the equatorial plane as well as the path of the sun.
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