A simple experiment will allow you to see how the seasons change as the Earth travels around the sun. You will need a globe and a lamp. Set the lamp in the middle of a darkened room and remove the shade so that the bulb is exposed. Place the globe on a table or a stand about 2 feet (60 centimeters) away from the lamp and at about the same height.

Tilt the globe so that the North Pole is pointed toward the light at about a 25-degree angle. This represents summer in the Northern Hemisphere. Now rotate the globe slowly on its axis. You will notice that more light falls directly on places in the Northern Hemisphere than on those in the Southern Hemisphere. The light falls on the North Pole continuously, but it does not reach the South Pole at all.

Now carry the globe slowly around the lamp, facing the light and keeping the base of the globe turned exactly as it was when you started. Observe where and how the light falls. You will notice that when you reach a point opposite from where you started, the Southern Hemisphere receives more direct light from the lamp. At that point it is summer in the Southern Hemisphere and winter in the Northern Hemisphere.

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