Since the beginning of time, some people have believed that the earth is flat. beginning around 300 b. c., however, some began to wonder if the earth is actually spherical in shape. those that favored the flat earth theory made the following observations: the earth is stable because it is a flat landmass sandwiched between a flat layer of air and a flat layer of water. if the earth is spherical, then oceans should be curved on top, but they aren't. some rivers flow for hundreds of miles but only fall a few feet. the rivers should fall farther if the earth is spherical. if the earth is spherical, people and animals that inhabit the earth would notice as they walked along its surface. since mariners are able to use flat compasses to navigate their ships without crashing, the earth must not be a sphere. those that disputed the flat earth theory countered the claim by observing that christopher columbus was able to sail around the earth without falling off the edge and later, by presenting satellite imagery taken from space of a spherical earth. this example demonstrates that