Astrolabe of Ibrahim ibn Said al-Sahli

A brass astrolabe signed by Ibrahim ibn Said al-Sahli and dated 459 in the Islamic calendar, which is 1067, made in a workshop in Toledo. The pierced star map on the front, called the rete, rotates over a plate engraved for a particular latitude, so a user could tell the time from a star's height or work out when a star would rise. The long rule across the face helps read off the scales. It is in Madrid's National Archaeological Museum.