Objects / Celestial instruments

A sky small enough to hold

A scientific instrument can also carry a culture’s understanding of the heavens.

A planispheric astrolabe brings a representation of the sky onto a flat surface. Its rotating components allow a user, given the appropriate initial information, to perform calculations involving celestial positions and time.

Historical uses included telling time, measuring latitude and determining prayer times and the direction of Mecca. The instrument made astronomical knowledge portable.

Read the object in layers

The Metropolitan Museum of Art describes an astrolabe as stacked circular plates rotating around a central pin. The upper openwork plate, or rete, could be richly decorated. Markings, pointers and ornament deserve attention together: the object was both a working instrument and an expression of craft.

When looking at one in a museum, ask what moves, what is engraved, and what information a user would have needed. These questions turn a beautiful surface into a readable device.