The ancient Greeks knew that the planet was essentially spherical. But even they did not know its curvature by ordinary observation. They had to use mathematics to do so, as well as some facts, such as the fact that the tops of sails appear first when a ship sails.

Even today, when we look at a sprawling landscape of endless prairies, savannas, or oceans, it appears to be a perfectly flat surface. Walking or navigating on it certainly does not feel like a curved surface.

This fact is the main reason why some people today still believe the earth is flat. After all, they might say, look at the ocean here – it is perfectly flat, there are no curves whatsoever. It looks that way to us. But the other side of the coin is the fact that we don\’t know why it is so.

The reason the earth looks flat to us is the difference between the size of the earth and ours. Simply put, we are so small compared to this planet that we cannot perceive its curvature. It sounds incredible, but it is true. And we can show that this principle works with a simple experiment.

All you need for the experiment is a camera large enough to zoom and focus and a round object like a ball. The larger the object, the easier the experiment will be. Use the camera to capture a portion of the round object. Notice the magnitude of the curvature. The curvature can be measured.

Next, use the zoom function to bring the image back into focus. This time we can see a much smaller portion of the ball, but we can also see that the curve has contracted. Repeat this process until the zoom is at its maximum possible. You will see that the closer you get, the smaller the curvature becomes. And this is how it works on a planetary scale. Like it or not, we are too small to see this stuff. It is that smallness that we should be aware of.