his book, On Learned Ignorance (1440). Aryabhata (476-550), Brahmagupta (598–668), Albumasar and Al-Sijzi , also proposed that the Earth rotates on its axis. The first empirical evidence for the Earth's rotation on its axis, using the phenomenon of comets , was given by Tusi (1201-1274) and Ali Qushji (1403-1474). Tusi, however, continued