Astrolabe, Spain or North Africa, 1236/37. Brass. Adler Planetarium, Chicago, IL, M-35. Photograph courtesy of Adler Planetarium

Astrolabes served many functions in the Islamic world. These highly sophisticated instruments were used to wayfind, tell time, survey land, and verify the direction of Mecca, which Muslims face when praying. The astrolabe was also used to calculate the relative position of stars and planets.