Question

How did the sailors find out that the earth is round?

Answer 1

$\huge\mathcal\red{HERE'S YOUR ANSWER }$

Earlier people thought that earth was flat and they would fall if they move towards its edge but once many scientists worked on it and explorers sailed the globe continuously they came to know that earth is not flat..

Answer 2

The idea of the Earth being a flat disc is also inconsistent with the fact that a given lunar eclipse is only visible from half of the Earth at a time. The only shape that casts a round shadow no matter which direction it is pointed is a sphere, and the ancient Greeks deduced that this must mean the Earth is spherical.