Experiment:

In order to do this experiment well, you will need a globe on a tilted stand. You will also need a flashlight.

If you do not have the appropriate globe, click on the following link to look at ours. The steps within the experiment should still make sense.

Step 1: Position the globe and stand such that the north pole is pointed toward you.
Step 2: Turn off the lights and close the shades
Step 3: Shine the flashlight at the tropic of cancer (just north of the equator)
Step 4: Spin the globe and maintain light on the tropic of cancer
Step 5: As the globe spins, observe the following
            I. Missouri-goes through periods of light and dark, as does most of the world
           II. North Pole-stays in the light
          III. South Pole-stays in the dark

Here is what happens. ½ of the Earth will be in sunshine at all times. If the axis of the Earth's rotation were not tilted, all locations on earth would receive 12 hours of daylight and 12 hours of darkness each day (see the image below).

The axis of the Earth's rotation is tilted and thus the image to the right is not true.

Notice that the North Pole will rotate in this example, however it never crosses over to the unlit side of the planet. Also note that the South Pole is in darkness in this example and will not cross over to the lighted side of the planet.