On the ground, the sun will eventually disappear beyond the horizon. Or even start laying down and then stand up. Find a spot where you can see the sunset, and also have a place close by where you can safely move higher, such as a tree or building. One way to test this is to watch the sunset. Things in the distance are not visible because there is a curve to the landscape. And a ship will slowly start to disappear from view as it gets farther away. We can’t look out into the distance and see a town that’s miles away. However, if we look out when standing on the ground, we can’t see that far. The boat would stay in view no matter how far out to sea it went.

We could see another city that’s hundreds of miles away. If the Earth was flat, we would be able to look out and see very far, assuming that there were no buildings in the way.

It turns out that we can test many of these reasons out for ourselves, too.

There are a number of reasons why scientists know that the Earth is round, and not flat. This is why some parts of the world have day and night at different times. As the Earth rotates, part of the Earth is facing the sun, and part of it faces away. It rotates around its own axis slowly but continuously, and completes this rotation about once every 24 hours. Like the other planets, the Earth is a sphere.

Evidence that the earth is not flat