Nasir al-Din al-Tusi

Known for

Maragha observatory; the 'Tusi couple'; trigonometry as an independent subject

Biography

Persian polymath from Tus who persuaded the Mongol ruler Hulagu Khan to build the Maragha observatory.

Contributions

• Directed the Maragha observatory (founded 1259), a major research centre with a large library
• Invented the Tusi couple, a geometrical device later found in Copernicus's work
• Treated trigonometry as a subject separate from astronomy
• Produced the Ilkhanic astronomical tables

Major works

• Zij-i Ilkhani
• Al-Tadhkira fi 'Ilm al-Hay'a (Memoir on Astronomy)
• Treatise on the Quadrilateral