>>11313461>How do you know if the surface of Earth is convex or concave?Go to the beach and watch some ships coming in close to shore. You will see the top first. Since you can see the top before the bottom, that means there is a convex surface in between you and the ship (the ocean). If the ocean was concave, you'd be able to see the ship from a top view from a distance, and gradually see less of it as it got closer until it was a side view.
