The tilt of Earth’s axis — Earth’s axis is tilted at about 23.5° relative to its orbit around the Sun. This tilt means that different parts of Earth receive varying amounts of sunlight at different times of the year.

• When the Northern Hemisphere is tilted toward the Sun (around June), it experiences summer — longer days and more direct sunlight.

• When it’s tilted away (around December), it experiences winter — shorter days and less direct sunlight.

Earth’s revolution around the Sun — As Earth travels around the Sun once every year, the orientation of the tilt causes the Sun’s rays to strike different latitudes more directly at different times. This changing angle of sunlight affects both the intensity of heating and length of daylight.