Nasir al-Din al-Tusi

Persian polymath whose astronomical models influenced Copernicus and revolutionized planetary theory

Nasir al-Din al-Tusi (1201–1274) reshaped astronomy with his Tusi Couple—a geometric model that explained linear motion through circular orbits. This breakthrough resolved Ptolemy's inconsistencies and directly informed Copernicus' heliocentric theory.

As founder of the Maragheh Observatory, al-Tusi compiled the Ilkhanic Tables, the most accurate astronomical data until Kepler. His mathematical innovations in trigonometry, including the law of sines for spherical triangles, became foundational for celestial navigation.

Beyond astronomy, al-Tusi authored over 150 works in ethics, philosophy, and medicine. His Akhlaq-i Nasiri (Nasirean Ethics) synthesized Greek and Islamic thought, while his biological classifications predated Linnaeus by five centuries.

Surviving the Mongol invasions, al-Tusi persuaded Hulagu Khan to support scientific research—a testament to his diplomatic and intellectual influence. Historians credit him with preserving and advancing knowledge during Islam's Golden Age transition to Europe.