Why do you think the earth is a sphere?

It can only be proved from a physical point of view that when you climb high and see far, the earth is a sphere. In low places, the line of sight is not wide, but in high places, there is no other object to stop, so you can see farther. The earth is a sphere, so you can overlook it.

Climbing high and seeing far can only prove that the earth's surface has curvature. If the earth is a plane, the distance between standing on the ground and standing on the tower is different. The phenomena that can prove that the earth is a sphere are:

1. Look at the sail in the distance first, and then at the sail body in the ocean.

The farther south you go in the northern hemisphere, the lower the height of Polaris, but you can't see Polaris in the southern hemisphere.

The phenomenon of solar eclipse shows that the shadow of the earth is spherical.

4. Travel around the world.

5. Satellite images.