His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres, in which he used the epicycles of his planetary model to compute the dimensions of the universe.
Hans planetariske hypoteser gik ud over den matematiske model i Almagest ved at præsentere en fysisk gengivelse af universet som et sæt af indlejrede sfærer, hvor han brugte epicycler i den planetariske model til at beregne dimensionerne af universet.