An Effect of Earth's Tilt

Earth’s axis is always tilted in the same direction. However, when Earth orbits the Sun, sometimes the top part of the axis is tilted toward the Sun. Other times, the top part of the axis is tilted away from the Sun. The tilt affects how much sunlight reaches the northern hemisphere.

The diagrams on the right show how much of the northern hemisphere is lit up by the Sun in June and in December.