When you think about a time when the answer to the question "Is the Earth really round?" could possibly be in dispute, you probably think back to the Middle Ages. If you were to tell someone back then that the Earth is shaped less like a plank of wood and more like an orange, they'd probably say something like, "Get to Church you blathering, godless heathen!" or "The Earth has been, and always will be, flat!"
That seems like the last time it would be acceptable to think the Earth is flat, right? But somehow, people still believe the Earth is flat.
Roughly 600 years later.
The same year that one can get on a magic screen, visit a store that doesn't even physically exist, click the image of a telescope, have said telescope delivered within an hour, and use that telescope to look at more spherical planets in the sky, just like ours.
But, alas, there are some - like those folks in the Middle Ages - that just aren't buying it.
So, why do people believe in a flat Earth? Click through to find out how shallow the rabbit hole is, and why "flat-Earthers" don't believe you'll end up on the other side.