Concentric spheres

The cosmological model of concentric or homocentric spheres, developed by Eudoxus, Callippus, and Aristotle, employed celestial spheres all of which had the same center, the Earth.^[1][2] In this respect it differed from the epicyclic and eccentric models with multiple centers, which were used by Ptolemy and other mathematical astronomers until the time of Copernicus.

Notes

1. ^ Neugebauer, Otto (1975), A History of Ancient Mathematical Astronomy, 2, Berlin / Heidelberg / New York: Springer-Verlag, pp. 677–85, ISBN 0-387-06995-X 
2. ^ Lloyd, G. E. R. (1999) [1996], "Heavenly aberrations: Aristotle the amateur astronomer", Aristotelian Explorations, Cambridge: Cambridge University Press, pp. 167–8, ISBN 0-521-55619-8