How 9th century Baghdad revived astronomy

It all started from the House of Wisdom, also known as Bayt al-Hikma, which was founded by the fifth Abbasid Caliph, Harun al-Rashid in Baghdad in the 8th century.

The place became a melting pot of knowledge with philosophers, thinkers and astronomers from different quarters of the world taking refuge in this intellectual powerhouse. 

Once the Abbasids came to power in Iraq following their victorious revolution in 750 AD against the Umayyad Caliphs, their new capital was moved from Damascus to Baghdad. It was the time when Muslim conquests and imperial growth was allowing a dynamic cultural climate to expand.  

As a result, various intellectual traditions were composed under the Muslim rule which gave a platform to ancient Greek learning from Europe, as well as that of the Persians, Sumerians and Indians in the East.

For five centuries, between the 8th and the 13th century, Europe was suffering from intellectual decay while Baghdad was a city on a hill, a shimmering example of knowledge-sharing and scientific feats.

The House of Wisdom hosted people from around the world and from different faiths— Christians, Jewish, Muslims, Zoroastrians —who collected and translated numerous works from the Greek literary canon, which established an enormous influence on Arab thought. 

Al Mamun, the seventh caliph, brought the works of Plato, Aristotle, Ptolemy, Hippocrates and Euclid from the west and had them translated word by word at the House of Wisdom, which housed a massive library with various galleries devoted to each scientific branch. 

During his reign, Al Mamun put his enormous power and wealth in the service of scientific discovery. The caliph and nobles of his palace paid an enormous amount of silver to carry out the vital work of transmitting ideas from ancient Greece, India, Persia and Syria into the Arabic tradition. 

Since obtaining copies of these books was vital to improve the capabilities of the House of Wisdom, Al Mamun personally wrote to the Emperor in Istanbul (Constantinople) asking him to send ancient texts so he could have them translated into Arabic.

"At this time, astrology was held in the highest esteem as a science in Arab society. The stars and planets were perceived to influence events on earth and astrology was thus carried out with the greatest attention to detail," writes Isabella Bengoechea, a journalist at The Times. 

Scientific studies related to astronomy therefore took place following the establishment of the House of Wisdom. Renowned Muslim scholar Al Khwarizmi was among those scientists widely credited for compiling the oldest astronomical tables and Caliph Al Mamum assigned him as the court astronomer. 

Al Mamun also paid for original scientific research which paved the way for the first observatory in the Islamic world that allowed Al Khwarizmi and other astronomers to record accurate observations of the celestial bodies, later building another one in Damascus so that data from the two could be compared. 

Al-Mamun had an astronomical observatory built with the intention of addressing the claims of one of the most dominant voices in the ancient world, Ptolemy. 

The Shammasiyah observatory was set up first in 828 on the orders of Caliph Al Mamun in Baghdad. It came under the purview of "the scientific academy of House of Wisdom."

In the following years, Baghdad earned the reputation of hosting great astronomers who possessed skills to observe "the moves of the sun, moon and planets which allowed them to present the results in a book called Mumtahan Zij." 

With the towering figures like the Banu Musa brothers, who achieved remarkable success in the field of science, astronomers in Baghdad developed the astronomical techniques for measuring "the maximum and minimum altitudes of the sun" while observing lunar eclipses. 

The Banu Musa brothers were gracious enough to pay "handsomely for translations and the acquisition of ancient books of knowledge."

Ursa Major, a bear-like constellation of stars, was also observed from a Baghdad observatory which was named after the Banu Musa brothers. 

Amid the environment of academic excellence, Al Mamun’s palace was often frequented by scholars and scientists of various disciplines. They had "lively debates which encouraged them to challenge one another and the ancient texts they studied," according to historian Violet Moller, who has written extensively about the subject. 

The team made up by Al Mamun even measured the length of the Earth's equatorial belt, and the only difference between the current value was 500 metres as there was no record of the size of their units of measurement, an exceptional scientific brilliance.

His astronomers set off in the middle of the night across the flat plain of Sinjar in Iraq, one group walking due north, the other due south, until they had measured one degree of the earth, before walking back towards one another carefully counting the distance.

Under Mamun’s influence, scientific discoveries blossomed in the Abbasid Empire. His vision, curiosity and charisma helped fuel one of the greatest intellectual epochs of all time. 

Eventually, Baghdad became an unrivalled centre for the study of humanities and sciences, including mathematics, astronomy, medicine, chemistry, geography, philosophy, literature and the arts – as well as some more subjects such as alchemy and astrology.

The Mongols destroyed the House of Wisdom along with Baghdad’s mesmerising reputation when they attacked the city in 1258.