Ptolemy’s Planisphaerium

• The ‘Planisphaerium’ is a Work by the Alexandrian Astronomer Ptolemy written in c.150 CE.
• It contains a description of the mathematical calculations needed to project the stars on to the celestial sphere.

Possible early Astrolabe

• This appears to be a guide to constructing an Astrolabe, but there is no proof that he built one.

Armillary Sphere

• However, Ptolemy did build an Armillary Sphere.