Rotation

Real World Example

Imagine you're trying to turn a stiff doorknob to open a door. Just like the doorknob spins around its central point to allow you to enter a room, a planet rotates around its axis, allowing different parts of its surface to face the sun throughout the day. The axis of a planet is like the central spindle of the doorknob, and as the planet turns on this axis, it creates the cycle of day and night much like opening the door lets you transition from one room to another.