The Earth is Flat

How do you know that it isn’t? Not long ago, I came across a comment to the effect that the Bible should not be trusted as any sort of guide because it was written¬† by men who believed the Earth is flat. I do not intend to defend the authority of the Bible in this post, or to speculate about divine inspiration, or even to consider whether the writers of the Bible did indeed believe that the Earth is flat. Instead I want to consider this idea that because people in ancient, and not so ancient, times knew less about the natural world than we moderns do, they were therefore more ignorant and more foolish than we are, and therefore have nothing worth saying to us.




English: The Flammarion engraving is a wood en...
Although it would be cool if you could see over the edge of the Earth.


So, I will ask again. How do you know that the Earth is round? No doubt you have seen photographs of the Earth taken from space. The Earth seems spherical enough. You might also have taken plane trips around the world, or at least a good portion of it. You might have traveled on a ship so far that you have returned to your starting place, and therefore realized that the Earth cannot be flat. Moreover, all the books and maps and globes say the Earth is a sphere. It is so obvious that the Earth is round that members of the Flat Earth Society must either be joking or among the most ignorant fools on the planet.




But, what if there were no pictures from space? What if there were no airplanes or ships capable of long ocean voyages? Could you, by your own observations be able to determine the true shape of the Earth? Probably not.




The truth is, that the idea that the Earth is flat is perfectly reasonable given the information that the people in ancient times had available to them. It is not at all obvious that the Earth is round and there is no reason for anyone prior to the development of modern science to even suspect that might be the case. The remarkable thing is that people in ancient times did learn that the Earth is a sphere.




It was the ancient Greeks who discovered the true shape of the Earth, and the way they learned this might not occur to many even in our enlightened times. The Greeks were a sea-faring people. You can see farther out on the sea since there are no obstructions like trees or mountains as there are on land. Greek sailors noticed that as a ship moved farther away, it did not just recede into the distance. First the hull of the ship vanished, than the bottom of the sail, and finally the top of the mast. Eventually someone realized that this observation meant that the Earth could not be flat, but must at least be curved. The discovery was attributed to Pythagoras (the one with the theorem) but it is possible that the knowledge of the Earth’s shape was known as far back as the time of Homer. Aristotle argued that the Earth must be round because the shape of the Earth’s shadow on the Moon during a lunar eclipse is round. Eratosthenes actually measured the circumference of the Earth with an amazing degree of accuracy. Contrary to what is still often believed, knowledge of the round Earth did not vanish during the “Dark Ages” nor did the Catholic Church ever teach that the world was flat.


English: Ship at horizon: due to earth curvatu...
English: Ship at horizon: due to earth curvature lower part is invisible. (Photo credit: Wikipedia)


There are two lessons to be learned here. First, as I said, the concept that the Earth is flat is perfectly reasonable and obvious if you have not been able to make the sorts of observations that would show otherwise. How many perfectly reasonable and obvious ideas do you think are widely held today that are simply wrong? Second, even though people in the past did not possess our modern knowledge of the natural sciences and technology, it does not follow that they were stupid or that they had nothing worthwhile to say to us. It may well be that in some ways they were wiser than we are.