Astrolabe of 'Umar ibn Yusuf ibn 'Umar ibn 'Ali ibn Rasul al–Muzaffari, Rasulid period (1228–1454), dated A.H. 690 / a.d. 1291
Brass; cast and hammered, pierced, chased, inlaid with silver; case (a): Max. W. 7 5/8 in. (19.4 cm), Diam. 6 1/8 in. (15.6 cm), D. 1/4 in. (0.6 cm)
Bequest of Edward C. Moore, 1891 (91.1.535a–h)
Invented in ancient Greece, the astrolabe is a sophisticated tool for observing the position of the stars. In early Islam, when scientific studies flourished, astrolabes were vastly improved and came to be used to determine the correct times for Muslim prayers as well. Through Islamic Spain, the astrolabe was introduced to Europe, and in the Middle Ages sailors, both Islamic and Christian, employed the device to stay the course of their sea routes.