Here's why:

* Earth's Rotation: The Earth rotates on its axis, causing day and night. As the Earth turns, the sun appears to move across the sky.

* Sun's Position: At sunrise, the sun is rising in the east and is at its lowest point in the sky relative to the horizon. At sunset, the sun is setting in the west and is again at its lowest point in the sky.

Let me know if you have any other questions!