Ibn Yunus

General Information:

Ibn Yunus was in a family of scholars, his father Abd Al Rahman was being noted as a historian, Ibn Yunus’s full name is Abu’l-Hasan Ali ibn Abd al-Rahman ibn Ahmad ibn Yunus al-Sadafi. Information about his early life and education is uncertain but we know for sure is that he was born in Egypt between 950 and 952 and came from a respected family in the Fustat; the Fustat is actually Cairo nowadays. As a young man he witnessed the Fatimid conquest of Egypt and the foundation of Cairo in 969. “He served two Caliphs of the dynasty, Al-Aziz and Al-Hakim, making astronomical observations for them between the years of 977-1003.” His major work Al-Zij Al-Hakimi AlKabir was dedicated to the second Caliph he worked for, Al-Hakim.  Al Zij is an astronomical handbook with tables; this significant work is what made him famous and influential. Through his Hakimi Zig he reached a high level of complication in trigonometry, the Zij also outlines several formulae for use in spherical astronomy. The Zij was unusual because it records a large number of observations, both Ibn Yunus’s own and those of previous observers.  Ibn Yunus’s Zij was intended to replace the Mumtahan Zij of Yahiya ibn Abi Masur, prepared for the Abbasid Caliph Al-Ma’mun in Baghdad 200 years before. Ibn Yunus often compared his own observations with the other observations in the other old Zij. He is nowadays described as an “eccentric, careless and absent-minded man who had a comic appearance”. One day in the year 1009 when he was in good health, he predicted his own death after exactly 7 days, a week. He locked himself in his house and “washed the ink off his manuscripts and recited the Quran until he died on the same he had predicted.