The sun is a star. It remains in the same place. The earth rotates on its axis once in twenty-four hours. When one side of the earth is turned towards the sun it will be daylight on that side and night on the opposite side. The earth itself blocks out the sunlight and makes it possible to see the stars in the nighttime sky. The sun appears to be rising in the east in the morning and setting in the west in the evening because of the way the earth rotates. The earth also revolves around the sun in an orbit that takes one year to cover. Because the earth is tilted on its axis, the northern hemisphere gets more exposure to sunlight when the earth is tilted towards the sun in its orbit and the southern hemisphere gets more when it is tilted towards the sun. So the seasons in both hemisphere are determined by the earth's revolution around the sun, while day and night are determined by the earth's rotation on its axis.
Nothing really happens to the sun at night. Instead it is what happens to the part of the Earth where it is night. The earth is always turning, and the part that is turned away from the sun and is in shadow is called night. The sun is shining just the same in other parts of the world at the same time that you have night.
nothing, it stays in place. it is the earth that rotates till sunlight can't be seen anymore from and to a certain point.