Planispheric astrolabe

The astrolabe is a two-dimensional model of the universe, used to tell time by measuring the altitudes of the sun or a selected fixed star at a given moment. Originating with the Greeks (its name comes from the ancient Greek astrolobos, “star-taker”) and refined by Muslim astronomers in the Middle Ages, it was one of the most important and versatile early scientific instruments. Beyond time-telling, its uses ranged from navigation to charting horoscopes, and it served as inspiration for later astronomical clocks like the one in this case. Signed and dated, this astrolabe is one of the earliest known European examples.