You probably believe that the earth is spherical, but as we look around, it certainly appears that the earth is flat. One classmate suggests that if you call someone on the "other side" of the world by phone, they can verify that it is midnight there when it is noon here. Another student reminds you of the picture taken of the spherical earth from the moon landing. Your teacher explains the ancient observation that when the sun was directly overhead on one day near the equator, a pole some hundreds of miles away to the north still cast a shadow. What, then, is the best scientific basis for considering that the earth is spherical?
