Certainly not as early as Columbus sailed around the globe. The first person to suggest that the earth should have a spherical shape was the Greek mathematician Pythagoras, and later the Greek philosopher Aristotle explained in practical terms why the earth should be spherical. During the eclipse, Aristotle realized that the earth was between the moon and the sun, and that in each eclipse the earth’s shadow on the moon was always circular. Aristotle believed that if the earth were a large circle, as many people are saying, it should be in a straight circle only when the sun was shining directly on it, and when it was tilted, it should be elongated.