Khwaja Naseer od-Din Tusi

Compiled by: Syed Ali Shahbaz
On 6th of the Islamic month of Shabaan in 1274 AD, the famous Iranian Islamic religious scholar and scientist, Mohammad ibn Mohammad ibn Hasan Tusi, popularly known as Khwaja Naseer od-Din, passed away at the age of around 75 years in Kazemain, Iraq, and was laid to rest in the holy mausoleum of Imam Musa al-Kazem (AS), the 7th Infallible Successor of Prophet Mohammad (SAWA).
Born in Tous, near the holy city of Mashhad in Khorasan, northeastern Iran, he was an outstanding philosopher, scientist, mathematician and astronomer, who made rich contributions to world culture and civilization. Even the Mongol invaders acknowledged his genius and Hulagu Khan, appointed him as his scientific advisor.
Naseer od-Din Tusi built the famous observatory at Maraghah. It had various instruments such as a 4-meter wall quadrant made from copper and an azimuth quadrant which was his unique invention. Using accurately plotted planetary movements, he modified Ptolemy's model of the planetary system based on mechanical principles. The observatory and its library became a centre for a wide range of work in science, mathematics and philosophy.
He wrote some 80 books on various subjects including theology (Tajrid al-E’teqad), ethics (Akhlaq-e Naseri), philosophy (Sharh al-Isharaat Ibn Sina), mathematics (Kitab ash-Shakl al-Qatta), astronomy (at-Tadhkirah fi Ilm al-Hay'ah) etc, in both Arabic and Persian. It is to be noted that a 60-km diameter lunar crater located on the southern hemisphere of the moon is named after him as "Naseereddin". A minor planet discovered by Soviet astronomer Nikolai Stepanovich Chernykh in 1979 is named after him “10269 Tusi”