Two proofs about the shape of the earth are:
- All celestial bodies are spherical — Spheres are the only geometrical shapes that are circular in outline. Sun, Moon amd all other celestial bodies appear to have circular outline. Since Earth too belongs to the same system, there is no reason why Earth should be an exception.
- Circumnavigation of the earth — Time and again people travelling round the world in different directions came back to the starting point.