20 Lira Ali Qushji

Ali Qushji — properly Alauddin Ali ibn Muhammed Qushji — was the fifteenth-century Ottoman astronomer and mathematician who served at the Samarkand observatory under Ulugh Beg before fleeing to Istanbul following his patron's assassination in 1449. His treatise Risale fi'l-Hey'e notably argued that Earth's motion could not be disproved through purely physical reasoning, a position that prefigured Copernican debate by decades. The Turkish Mint has issued him in a series honoring Islamic scholars of science, a program running since the early 2010s.