1Two things the Earth is doing
Earth spins — and Earth leans
You only need two ideas. Watch each one move:
It spins once a day
That spin is what makes day and night. As your city rides around, it swings into the Sun's light, then around into the dark, then back — once every single day.
It leans over a little
Earth doesn't spin straight up — it tips a bit. And it keeps leaning the same way all year. Only which side of the Sun we're on slowly changes.
2Two pretend Earths
The straight-up world vs the leaning world
To find out what the lean does, imagine two Earths side by side. The Sun shines from the right on both. The bright side is day, the dark side is night.
The straight-up world
The day/night line splits every city's ring right down the middle — half light, half dark.
The leaning world
The lean tips the top toward the Sun, so a northern city's ring slides into the bright side.
3Your turn — ride the spin
Drag your city around one whole day
Here's the real, leaning Earth in summer. Your city rides a ring around the spin axis once a day. Drag the slider to walk it through a full day and watch when it's in the sunlight and when it slips into the dark.
4Now run the real test
Turn the lean off — does the long day stay? 🌍
Same northern city, but now there's one switch: Earth's lean. Stand the planet straight up, then tip it back over, and watch the whole day-ring — and the clock. But guess first.
Guess before you flip the switch
Is Earth's lean really what makes summer days long — or would they happen anyway, even on a straight-up Earth?