Signed by Yunus Ibn al-Husayn al-Asturlabi
Celestial sphere
Iran, Isphahan?
1144-1145
Cast copper alloy, engraved and silver-incrusted
MAO 824

A celestial sphere is a three dimensional model of the universe. The celestial coordinates are materialised by the metal sphere on which are even figured to 48 constellations described by Ptolemy whose iconography has been orientalised in many details, but which remains quite identifiable. The terrestrial coordinates are shown in the form of a horizon circle - here replaced - and a meridan circle now lost. Each of the constellations is accompanied by its name engraved in arabic, and within, each of the stars, indicated by a silver circle, has a number which refers to that of a catalogue of stars. The catalogue which was used by Yunus as a reference is, as attested by the inscription, that of the Almagest of Ptolemy whose first arabic translation goes back to the end of the VIIIth century. The quality of the engraving makes this globe both a remarkable scientific instrument and a masterpiece.

Preserved at the Louvre Museum.