Sphaera Mundi

Sphaera Mundi

De sphaera mundi (Latin meaning On the Sphere of the World, sometimes rendered The Sphere of the Cosmos; the Latin title is also given as Tractatus de sphaera, or simply De sphaera) is a medieval introduction to the basic elements of astronomy written by Johannes de Sacrobosco (John of Holywood) c. 1230. Based heavily on Ptolemy's Almagest, and drawing additional ideas from Islamic astronomy, it was one of the most influential works of pre-Copernican astronomy in Europe.