User:Jomoakin/sandbox
From Wikipedia, the free encyclopedia
For the album by Wormed, see Planisphaerium (album).
The Planisphaerium is a work by Ptolemy. The title can be translated as "celestial plane" or "star chart". In this work Ptolemy explored the mathematics of mapping figures inscribed in the celestial sphere onto a plane by what is now known as stereographic projection. This method of projection preserves the properties of circles.