Planispheric astrolabe, Syrian, 9th century.
© Science Museum / Science & Society Picture Library
This unsigned bras Islamic astrolabe is from the Middle East and is probably of Syrian origin. An astrolabe is in esence a model of the universe that an astronomer could hold in their hands. From its origins in the Ancient World, Islamic astronomers developed the astrolabe and its use spread. Popular in Medieval and Renaisance Europe, its many uses included timekeeping, astrology and surveying. The two-dimensional depiction of the heavens used on this instrument is achieved using the mathematical technique of stereographic projection. This front view shows the moveable fretwork plate called the 'rete', which denotes the star positions by straight, tapering pointers.