Al-Biruni: The 10th century polymath who navigated the universe
4 min read
21 February, 2023

Abu Reyhan Al-Biruni was an astronomer, philosopher and mathematician extraordinaire, remembered for finding a method to measure the Earth's radius and discovering how the Earth revolved around the Sun.

According to Tajik academic Bobojon Gafurov, Al-Biruni was "so far ahead of his time that his discoveries seemed incomprehensive to most of his contemporaries." Gafurov would later use his platform at UNESCO to describe Al-Biruni as a "universal genius".

George Sarton, notable as the founder of the History of Science discipline, credited the 11th century as "the age of Al-Biruni".

"Al-Biruni said that his experience in the study of astronomy, geometry and physical experiments revealed to me that there must be a Planning Mind of Unlimited Power. My discoveries in astronomy showed that there are fantastic intricacies in the universe, which prove that there is a creative system and meticulous control"

Al-Biruni's works addressed several areas of science, with his extensive knowledge of ancient Greek enabling Al-Biruni to conduct comparative experiments; from Aristotle to Euclid, Ptolemy and Archimedes, Al-Biruni was able to compare and contrast their studies with command. 

While religious fanaticism swept across Europe, Al-Biruni – as a forerunner of the Renaissance – was way ahead of their knowledge production.

As discussed by Turkish professor Fuat Sezgin, the meeting of 27-year-old Al-Biruni and 18-year-old Ibn would be a seismic moment in the history of science. They would discuss the "propagation of light and its measurement" in great depth, with this meeting resulting in Al-Biruni being called "al-Ustad" – master par excellence. 

Al-Biruni's most remarkable achievement was measuring the Earth's radius. To do so, he measured the height of a hill in what is now the Punjab province of Pakistan. Later, Al-Biruni climbed a hill close to the Fort of Nandana to measure the horizon. Using trigonometry and algebra, Al-Biruni came to the value of 3827.77 miles, which is 99% correct of today's value.

He would also start uncovering the true relationship between the Earth and the Sun. Prior to Al-Biruni, many still believed the Sun revolved around the Earth. He would write about the inverse and would comment on the Sun's movements and the notion of an eclipse. To achieve this, Al-Biruni invented a number of astronomical models and diagrams that described how the Earth rotated on an axis.

Al-Biruni's masterpiece, Al-Athar Al-Baqiya included all of these theories and observations, including determining different directions, ascertaining the beginning of the seasons, and how much of the Sun was eclipsed during lunar and solar eclipses.

At Ghazni, now in modern-day Afghanistan, Al-Biruni observed the lunar eclipse and gave accurate details of the error-free altitude of various well-known stars at the moment of first contact. In doing so, he would poetically describe the Milky Way as a collection of countless fragments of nebulous stars. 

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The "universal genius" would also contribute toward physics, working on springs and the exact determination of specific weights of elements including metals and precious stones. Another of his works Kitab Al-Jamahir includes information about the properties of precious stones. 

He is also known for pioneering trigonometry, with studies on shadows and chords of circles as well as a method for trisecting an angle have been met with acclaim, and for his work on geography and anthropology with Eduard Sachau, the famous 19th-century German orientalist translating his book Al-Ahar Al-Baqiyah fi Qanun al-Khaliyah which was concerned with history and geography.

In summarising his work, Al-Biruni said that his "experience in the study of astronomy, geometry and physical experiments revealed to me that there must be a Planning Mind of Unlimited Power. My discoveries in astronomy showed that there are fantastic intricacies in the universe, which prove that there is a creative system and meticulous control that cannot be explained through sheer physical and material causes."

Ufuk Necat Tasci is a political analyst, journalist, and PhD Candidate in International Relations at Istanbul Medeniyet University. His research focuses on Libya, proxy wars, surrogate warfare, and new forms of conflict.

Follow him on Twitter: @UfukNecat