Distant things look dim and small

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Q1: Why do the Sun and the Moon look much the same size?

[Answer]

Any light leaving a surface spreads out in all directions. If we are close to it we get much of this light, and so the surface looks bright. But if we are far away, we get just a tiny part of this light and so the surface looks dim.

If we are close to an object, it fills most of our field of view and so looks large, but if it is far away, it fills only a part of the view and so seems small.