The acclaimed Muslim physicist, mathematician, and astronomer, Ibn al-Haytham,
On 13th of the Islamic month of Jamadi as-Sani in 430 AH, the acclaimed Muslim physicist, mathematician, and astronomer, Abu Ali Hassan ibn al-Hassan ibn al-Haytham, passed away in Cairo at the age of 76 years. He was born in the city of Basra in Iraq, which was then a province of the Iranian Bouyid Empire. He was also an authority on medicine, philosophy, and theology, having studied in Basra and Baghdad during the Golden Era of the Islamic Civilization.
He conducted extensive research on light rays. His influence on physical sciences in general, and on optics in particular, has been held in high esteem and, in fact, ushered in a new era in optical research, both in theory and practice. Known as “Alhazen” to Medieval Europe, the Latin translation of his main work, Kitab al-Manazer (Book of Optics), exerted a great influence on Western science: for example, on the work of Roger Bacon, who cites him by name, and on Johannes Kepler and Galileo.
His research in catoptrics (the study of optical systems using mirrors) centred on spherical and parabolic mirrors and spherical aberration. He made the observation that the ratio between the angle of incidence and refraction does not remain constant, and investigated the magnifying power of a lens. He moved to Egypt which was then ruled by the Fatemid Shi'ite Ismaili dynasty and carried out major projects including effort to regulate the annual floods of the River Nile. He is credited with inventing the telescope centuries before the Europeans, and as is evident in his books, he determined that the shape of the Earth is spherical.