How do we know Earth is round?

 Everyone knows Earth is round. Most of the people can't fell Earth is round. Almostly, they feel Earth is square. (Everyone knows Earth is round) is only result of education. So how do we know Earth is round?

1.Boat

 Imagine that you are in port and one boat is going to horizon. And we can see that boat is a little bit going down. Earth is round, so we can see this scene.

2.Lunar Eclipse

 Do you know Lunar eclipse? Lunar eclipse is phenomena that when Sun-Earth-Moon is a straight line,Moon become obscured by  Earth's shadow. Earth's shadow's shape is round. So we can know Earth is round. 

3.Time difference

 Each place's time is different. When Korea's students go to school, London and Paris' children are sleeping. If Earth isn't round, at the same time sun is rise, and at the same time evening is coming. But each place's time is different. So we can know Earth is round. 

4. Questions

 And We may have some questions. Let's solve questions. 

1.If Earth is round, why we don't fall? 

Because of Earth's gravity.

2.Earth is turning fast. Why we don't thrown into space?

Because air is turnig same speed, too.

3.Why we can't feel Earth is round?

Because we are so small.