Made by Mohammad Amin ibn Mohammad Taher, Persian, active early 18th century; decorated by Abd al-A'immah, Persian, active early 18th century; Planispheric Astrolabe, 1715; brass; 11 1/8 x 7 1/4 x 1 3/8 inches; Saint Louis Art Museum, Museum Purchase 41:1926
Astrolabes were the means by which ancient astronomers charted the stars, tracked constellations, and predicted eclipses.