What evidence proves that Earth is round?
Pictures from space for one, the laws of gravity for two and the curved horizon for three - not to mention the planes that fly and ships that sail around the world on a regular basis.
Not only that, but now that we have access to space, the easiest way to prove the Earth is spherical is to leave it and view it from a distance. Astronauts and space probes have done just that. Every picture of Earth ever taken shows only a circular shape and the only geometric solid which looks like a circle from any direction is a sphere.
One of the oldest proofs of the Earth's shape, however, can be seen from the ground and occurs during every lunar eclipse. The geometry of a lunar eclipse has been known since ancient Greece. When a full Moon occurs in the plane of Earth's orbit, the Moon slowly moves through Earth's shadow. Every time that shadow is seen, its edge is round. Once again, the only solid that always projects a round shadow is a sphere.