However, Aristotle argued that since every lunar eclipse, the earth’s shadow was always circular, the circle was round, and that no matter what angle the sun shone on it, the earth’s shadow must be circular. Aristotle also noticed that the orbits of stars were different in different parts of the world. Therefore, based on these two considerations, Aristotle concluded that the earth is not just a circle but a sphere. In fact, his ideas were 100% correct. When we look at the stars around the equator, we can see that the stars are moving in a straight line from east to west, and in the polar regions we can see that the stars are moving in a circular motion.