4. Al-Farghani
(Died after 247H/861AD) 

Abu'l-Abbas Ahmad Ibn Muhammad Ibn Kathir al-Farghani, known in the West as Alfraganus, was born in Farghana and lived in Baghdad during the rule of the Abbassid Caliph, al-Mamun. He was one of the most distinguished astronomers who worked in the service of al-Mamun and his successors(24). Sarton said about him "He was still alive in 861AD"(25). Al-Farghani was a contemporary of al-Khawarizmi, Beni Musa and Sanad Ibn Ali.

Scientific Contributions

Al-Farghani was an astronomer, astrologist and engineer. He determined the diameter of the earth to be 6,500 miles, and found the diameters of the planets.

Aldo Milli says : "Al Farghani's measurements of planet distances and diameters were used by many other astronomers, namely Copernicus(26) as such, almost without change. Thus, this Muslim astronomer had a significant influence on the renaissance of astronomy in Europe. In year 861, the Caliph al-Mutawakkil, entrusted him with supervising the construction of the Nilometer at al-Fustat. He supervised it to completion and his name was written on it.

Major Works

Al-Fraghani left a number of valuable books, namely :

- Kitab Jawami Ilm al-Nujum wal Harakat al-Samawiya a book on thorough science of the stars and celestial motion, which was translated into Latin in the 12th century by Gerard of Cremona. It was as well translated in Hebrew. This book exerted a great influence on European astronomy in the period before Regiomontanus, the astro-mathematician who thrived in the 15th century. Translations of this book were edited and published several times during the 15th  and 16th centuries.

- Fi al-Usturlab (on the Astrolabe) and Al-Jama' wa Tafrik (Addition and Division) .