<Ul> <Li> The terrestrial region, according to Aristotle, consisted of concentric spheres of the four elements--earth, water, air, and fire . All bodies naturally moved in straight lines until they reached the sphere appropriate to their elemental composition--their natural place . All other terrestrial motions were non-natural, or violent . </Li> <Li> The celestial region was made up of the fifth element, aether, which was unchanging and moved naturally with uniform circular motion . In the Aristotelian tradition, astronomical theories sought to explain the observed irregular motion of celestial objects through the combined effects of multiple uniform circular motions . </Li> </Ul> <Li> The terrestrial region, according to Aristotle, consisted of concentric spheres of the four elements--earth, water, air, and fire . All bodies naturally moved in straight lines until they reached the sphere appropriate to their elemental composition--their natural place . All other terrestrial motions were non-natural, or violent . </Li> <Li> The celestial region was made up of the fifth element, aether, which was unchanging and moved naturally with uniform circular motion . In the Aristotelian tradition, astronomical theories sought to explain the observed irregular motion of celestial objects through the combined effects of multiple uniform circular motions . </Li> <Li> The Ptolemaic model of planetary motion: based on the geometrical model of Eudoxus of Cnidus, Ptolemy's Almagest, demonstrated that calculations could compute the exact positions of the Sun, Moon, stars, and planets in the future and in the past, and showed how these computational models were derived from astronomical observations . As such they formed the model for later astronomical developments . The physical basis for Ptolemaic models invoked layers of spherical shells, though the most complex models were inconsistent with this physical explanation . </Li>

A renaissance scientist considered possibly the greatest scientist of all time was .a0