By Islam El Shazly
Abu Abdullah Muhammad ibn Musa Al-Khwarizmi, not a lot is known about his life as a whole, well, except the little fact that he founded Algebra, and introduced the Zero and the Arabic numerals to the world. But he was more than that; he was a mathematician, an astronomer, a geographer, and a cartographer, and he has done a lot more than solve quadratic equations.
Al-Khwarizmi, was born in Khwarizm – Khiva – around 780 CE (164 AH) in modern day Uzbekistan, back then it was part of Greater Khorasan within Persia. He moved with his family to Baghdad, the centre of knowledge and learning in an age that is now known as the Golden Age of Islam, there he would rise in the ranks and eventually be at the head of the House of Wisdom.
The statue of Al-Khwarizmi in Uzbekistan. By Retlaw Snellac (Walter Callens), Flickr.
His contributions to the world are many, but it was his contribution to astronomy, geography, and cartography that led him here.
While at the helm of the House of Wisdom, he embarked on two more projects that are ranked second only to his work on Algebra. First of which was the authoring of Zīj Al-Sindhind (The Astronomical Tables of Sind and Hind). A colossal work consisting of approximately 37 chapters on calendrical and astronomical calculations and 116 tables with calendrical, astronomical and astrological data, as well as a table of sine values. It contains tables for the movements of the sun, the moon and the five planets known at the time. It marked the turning point in Islamic astronomy.
The original Arabic version is lost, but a version by the Spanish astronomer Maslamah Ibn Ahmad Al-Majriti (c. 1000) has survived in a Latin translation, by Adelard of Bath. Source.
Kitab Surat Al-Ard
He was then appointed by the Caliph Al-Ma’mun to head a consortium of 70 Muslim scholars to determine the length of a degree of latitude. The end result would be Al-Khwarizmi’s third major body of work: Kitab Surat Al-Ard (Book on the Appearance of the Earth) which was finished in 833. It is a revised and completed version of Ptolemy’s Geography, consisting of a list of 2402 coordinates of cities and other geographical features.
Using wooden rods as measures, the Caliph’s scholars travelled a north-south road until they saw a change of one degree in the elevation of the pole star. Their measurements resulted in an amazingly accurate figure for the earth’s circumference: 41,526 kilometres, or 22,422 nautical miles—the equivalent of 115.35 kilometres per degree. Source.
There is only one surviving copy of Kitab Surat Al-Ard, which is kept at the Strasbourg University Library. A Latin translation is kept at the Biblioteca Nacional de España in Madrid. The complete title translates as Book of the Appearance of the Earth, with its Cities, Mountains, Seas, all the Islands and Rivers, Written by Abu Ja’far Muhammad Ibn Musa Al-Khwarizmi, According to the Geographical Treatise Written by Ptolemy the Claudian.
It opens with a list of latitudes and longitudes, in order of weather zones; that is to say in blocks of latitudes and, in each weather zone, by order of longitude. The book never included a map of the world, however one Hubert Daunicht was able to reconstruct the missing map from the list of coordinates.
Hubert Daunicht’s reconstruction of Al-Khwarizmis planisphere. Wikipedia.
In the book, Al-Khwarizmi corrected Ptolemy’s gross overestimate for the length of the Mediterranean Sea from the Canary Islands to the eastern shores of the Mediterranean; which was overestimated at 63 degrees of longitude, while Al-Khwarizmi almost correctly estimated it at nearly 50 degrees of longitude. And unlike Ptolemy, he depicted the Atlantic and Indian Oceans as open bodies of water, not land-locked seas. Al-Khwarizmi thus set the Prime Meridian of the Old World at the eastern shore of the Mediterranean, 10–13 degrees to the east of Alexandria and 70 degrees to the west of Baghdad. Most medieval Muslim geographers continued to use Al-Khwarizmi’s prime meridian. Source.
It is argued that had Columbus the work of Al-Khwarizmi he might have avoided many mistakes, and he would have actually ended up where he wanted in the first place!
Legacy
By the time he died in 850 CE/235 AH, Al-Khwarizmi had left a wealth of books, manuscripts, papers, and treatises from trigonometry, to geography and astronomy, and from algebra and mathematics, to sundials, the astrolabe and history, to a study about the Jewish calendar and spherical astronomy.
There is no doubt; he was one of the greatest scientific minds that have ever lived.
For more about Al-Khwarizmi and his books:
Al-Khwarizmi by Dr. Ragheb Al-Sirgany (Arabic)
