How Can the San Be Covered by Clouds Since It Is Much Bigger Than the Earth?

Our hands are small. But if you put one hand over your eyes, you won't be able to see the sky. When we look at things, those near us always appear bigger than those farther away.

The sun is big but it is very, very far from us. it is like a disc. As cloud is much closer to us, it appears big and that's why it can cover the sun.