Explanation:

When the Northern Hemisphere is oriented toward the sun, that region of Earth warms because of the corresponding increase in solar radiation. The sun’s rays are striking that part of Earth at a more direct angle. It’s summer.

When the Northern Hemisphere is oriented away from the sun, the sun’s rays are less direct, and that part of Earth cools. It’s winter.

Seasons in the Southern Hemisphere occur at opposite times of the year from those in the Northern Hemisphere. Northern summer = southern winter.

Another picture of autumn trees reflected in a lake with small rowboats in it.

Autumn in New Jersey’s Pinelands, by our friend Jeanette York. She said this is her backyard.

The tilt in Earth’s axis is strongly influenced by the way mass is distributed over the PLANET. Large amounts of land mass and ice sheets in the Northern Hemisphere make Earth top-heavy. An analogy for OBLIQUITY is imagining what would HAPPEN if you were to spin a ball with a piece of bubble gum stuck near the top. The extra WEIGHT would cause the ball to tilt when spun.

Over long periods of geological time, the angle of Earth’s obliquity cycles between 21.1 and 24.5 DEGREES. This cycle lasts approximately 41,000 years and is thought to play a key role in the formation of ice ages – a scientific theory proposed by Milutin Milankovitch in 1930.