When the sun rises from the east in the morning and falls down in the west at dusk， it looks very round and big. But at noontime it looks small and the sunlight is strong. Does the size of the sun change three times a day？

　　When the sun rises and sets， there are things like mountains， trees and buildings beside it that make it seem very huge. When the sun is high above us in the sky， there is nothing that can be used to compare its size with the sun， so we feel it is smaller.