How can you, without leaving the Earth, understand that it is round?

For example, by the shape of the shadow cast by the Earth during lunar eclipses; by how gradually, as one approaches, a distant object appears on the plain or on the sea; by how the view of the starry sky changes when moving from the earth’s equator to the poles.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.