Why We Have Seasons
Explain that the seasons are caused by the tilt of Earth's axis during its orbit around the Sun, distinguishing this from the common misconception that seasons are caused by changing distance from the Sun
What a learner can do afterwards
- Explains that Earth's axis is tilted at about 23.5° relative to its orbit
- Describes how the tilted axis causes one hemisphere to receive more direct sunlight in summer and less in winter
- Refutes the misconception that distance from the Sun causes seasons by noting Earth is actually slightly closer to the Sun in January
The lesson
Earth doesn't stand up straight as it circles the Sun. Its axis, the imaginary line it spins around, is tilted about 23.5 degrees. That tilt keeps pointing the same direction all year, even as Earth travels around the Sun.
In June, the UK's side of Earth, the Northern Hemisphere, leans toward the Sun. Sunlight hits it more directly, so it's summer there. At the very same moment, Australia's side, the Southern Hemisphere, leans away from the Sun. Sunlight there is more spread out, so it's winter.
It's tempting to think summer happens because Earth moves closer to the Sun. That's not true. Earth is actually slightly closer to the Sun in January, right in the middle of the Northern Hemisphere's winter. Distance barely changes across the year. Tilt is what matters.
To remember it, picture the tilt, not the distance. Whichever hemisphere leans toward the Sun gets summer. The one leaning away gets winter.
Seasons come from Earth's tilted axis leaning toward or away from the Sun, not from how close Earth is to the Sun.
Watch it
Where it sits
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.