Seasons come from the lean, not from the distance
Watch the Earth go round the Sun with its axis pointing the same way all year. The half leaning towards the Sun gets it high in the sky and for longer — and that, not the distance, is summer.
Seasons come from the lean, not from the distance — the interactive part
One trip round is one year. The axis keeps pointing the same way the whole time, so the hemisphere leaning towards the Sun changes as the Earth moves.
- Midday Sun height in June
- 62.5°
- Midday Sun in December (below 0 means it never rises)
- 15.5°
What this scene shows, in words
One trip round is one year. The axis keeps pointing the same way the whole time, so the hemisphere leaning towards the Sun changes as the Earth moves.
- The Sun — a sphere giving off the light in this scene.
- Earth — a sphere orbiting sun 1 time per cycle, turning 6 times per cycle, on an axis tilted 23.5 degrees, with a day and night side, with lines of latitude, with 1 place marked on its surface: You.
The values above change as the scene plays and as you move the controls; they are read out again whenever it is paused.
Midday Sun height in June is 62.5 °. Midday Sun in December (below 0 means it never rises) is 15.5 °.
Same distance, different angle
The orbit here is drawn as a circle because that is very nearly what it is: the Earth is about three per cent closer to the Sun in January than in July, and the northern hemisphere's winter is in January. What changes through the year is the angle the light arrives at. Light coming in steeply is concentrated on a small patch of ground; the same light coming in at a slant is spread thinly over a much larger one.
The axis never turns to follow the Sun
Follow the drawn axis as the Earth goes round. It stays pointing in one fixed direction in space — it does not swing to face the Sun. That is why the same end of the planet leans towards the Sun for one half of the orbit and away from it for the other half, and why the two hemispheres have opposite seasons at the same moment.
Push Your latitude past 66.5° and watch the marked place stay lit through a whole turn at one side of the orbit, and dark through a whole turn at the other.
Check your understanding
Why is it warmer in summer?
Pick one to check yourself.