What is an astrolabe?
An astrolabe is a tool for measuring and calculating in widespread use from the 6th century. The astrolabe was popular throughout the Middle Ages for a variety of uses based on the measurements of planets and stars: calculating time of day, predicting sunrise and sunset, measuring distance or the height of objects, and also for navigation. The astrolabe was a feat of the incredible scientific and astrological knowlege of the medieval Islamic world. It was only later imported to the Byzantine Empire and, through Al'Andalus (Islamic Spain) to medieval Western Europe.
Astrolabes are fascinating objects that testify to the exchange of scientific knowledge across languages and cultures in the premodern world. For just one example, click below to read about the Verona Astrolabe, which has inscriptions in both Arabic and Hebrew, added over time by various users: