Is it cold in winter because the earth is farther away from the sun in December? No. In fact, we're actually closer to the sun in winter than in summer. It's the angle at which sunlight strikes the earth at noon each day that determines how much of the sun's energy we feel. The Summer Sun, Winter Sun exhibit encourages you to move a model earth closer to and farther from a light source and watch the energy meter change. Then tilt the earth's plane to your latitude's summer and winter angles. You'll see that the sun's energy must spread over a greater area in winter, leading to lower temperatures.