Planispheric astrolabe, 1572
Astrolabes are complex calculating instruments used for timekeeping, predicting the motion of heavenly bodies, astrology and surveying. They contain one or more plates carrying projections of the heavens for the observer's latitude. On top of the plates lies a traceried circle called a 'rete' with pointers for prominent stars, and an arm known as an ‘alidade’ for sighting distant objects. By rotating the alidade and rete, the astrolabe can be used to derive a number of measurements. Astrolabes were mentioned by the Greeks, though the earliest surviving examples are from the Middle East. This example dates from 1572. The inscription reveals it was used by Don Columbinus of Alfiano, a monk at Vallombrosa in Italy. On the back is a universal projection of the heavens, allowing this astrolabe to be used at any latitude. Astrology was important for some medical traditions such as Paracelsian medicine. It was believed that the planets could influence the body and the humours. It was also believed that the positioning of the planets could determine the most opportune time for treatment.
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The study of the stars, moon, and planets, interpreted as having an affect on everyday life.
Instrument designed to observe the positions and measure the altitude of celestial bodies; used from the 2nd century BCE, until superseded by sextant.