The Islamic-Iranian mathematician and astronomer, al-Bouzjani
Compiled By: Syed Ali Shahbaz
On 3rd of the Islamic month of Rajab in 388 AH, the Islamic-Iranian mathematician and astronomer, Abu'l-Wafa Mohammad ibn Mohammad ibn Yahya al-Bouzjani, passed away in Baghdad at the age of 60. He was born in in Bouzhgan (now Torbat-e Jam) in Khorasan in northeastern Iran. At the age of 19, he moved to Baghdad and remained there for the next forty years.
He made important innovations in spherical trigonometry, and his work on arithmetic for businessmen contains the first instance of using negative numbers in an Islamic text. He was the first to build a wall quadrant to observe the sky.
Bouzjani participated in an experiment to determine the difference in local time between his location in Baghdad and that of his famous contemporary, Abu Rayhan al-Berouni, who was living in Kath, Khwarezm, which is now part of the Central Asian Republic of Uzbekistan. The result was very close to present-day calculations, showing a difference of approximately 1 hour between the two longitudes.
The 3rd Lunar Inequality (the variation) was first discovered by Bouzjani, a fact admitted by the European scientist, Tycho Brahe, who often quotes this Iranian Islamic scientist's work. His "Kitab al-Majisti" (Almajest) covers numerous topics in the fields of plane and spherical trigonometry, planetary theory, and solutions to determine the direction of Qibla. The crater Abu'l-Wafa on the Moon is named after him. Bouzhaani wrote several books that have not survived, including “Tarikh-e Ilm al-Hesab” (The History of Calculus).