The Real Cause of the Seasons
Many people think seasons happen because Earth gets closer or farther from the Sun. But that's not true! Seasons happen because Earth is tilted on its axis by 23.5 degrees. This means that different parts of the planet get more or less sunlight at different times of the year.
How Earth's Orbit Affects the Seasons
Earth moves around the Sun in an elliptical orbit (an oval shape), but the distance from the Sun changes only a little. The real reason for seasonal changes is the tilt of Earth's axis. As Earth orbits the Sun:
- In summer, your part of the Earth tilts towards the Sun, bringing longer days and more direct sunlight.
- In winter, your part of the Earth tilts away from the Sun, making days shorter and colder.
- During spring and fall (equinoxes), both hemispheres get about equal sunlight, so temperatures are moderate.
How Earth's Tilt Changes Daylight Hours
The tilt of Earth also changes the length of daylight throughout the year:
- At the Equator, day and night are almost always the same length (about 12 hours each).
- In mid-latitude places (like the U.S. or Europe), days get longer in summer and shorter in winter.
- At the North and South Poles, there are times when the Sun never sets (24-hour daylight in summer) and times when it never rises (24-hour darkness in winter).
How Seasons Affect Temperature
The angle of the Sun’s rays also affects how warm it gets:
- In summer, the Sun is higher in the sky, and its light is more direct, so it heats the ground more.
- In winter, the Sun is lower in the sky, and its light is more spread out, so it doesn’t warm things as much.
This is why June is hot in the Northern Hemisphere but cold in the Southern Hemisphere—because the North is tilted toward the Sun while the South is tilted away.
Why Different Places Experience Seasons Differently
The effects of Earth's tilt and orbit are not the same everywhere:
- Near the Equator, temperatures stay warm all year because the Sun’s rays are always strong.
- In temperate zones (like North America, Europe, and parts of Asia), there are four clear seasons.
- In polar regions, summers have 24-hour daylight, and winters have months of darkness.
Animation by ME, took 20 hours to render.