Why Can't We See the Sun at Night?

During the day time we can see the sun， but we cannot see it after sunset. Why is that？ The earth revolves¹ all the time. During the day the earth faces the sun. As the earth turns its back to the sun， it becomes night and we cannot see it. It is the same as when you stand facing a lamplight， you can see it； but when you turn around， you are no longer able to see the light.