The astrolabe is a flat, brass analogue computer of the heavens that models the rotating sky on a disc, letting its user measure the altitude of stars and the Sun and read off time, latitude and the direction of distant places. Inherited from Greek antiquity, it was transformed by scholars in the Islamic world from the eighth century, who added precise star tables, new projections and gearing, and applied it to fixing prayer times and the qibla, the direction of Mecca. Workshops in cities such as Baghdad, Isfahan and Toledo produced finely engraved instruments that spread into Europe through Islamic Spain. It became the emblematic scientific instrument of the medieval world.
The astrolabe gave cities a portable means of determining time, latitude and orientation, underpinning timekeeping, navigation and the precise alignment of mosques and streets toward Mecca. Through Islamic Spain it carried Greek and Arabic astronomy and surveying technique into European practice.
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