You only need two ideas. Watch each one move:
Try the ingredient below. Make a prediction before you compare the completed cases.
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.
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.
4Two 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.
No lean
The straight-up world
The day/night line splits every city's ring right down the middle — half light, half dark.
Real lean
The leaning world
The lean tips the top toward the Sun, so a northern city's ring slides into the bright side.
5So is leaning better?
Each world trades something away
The leaning world gives you summer
Long bright evenings, a high warm Sun, and a year full of changing seasons — all because your half of the planet tips toward the Sun.
The catch: the very same lean tips you away six months later, so summer's long days are paid back with short, dark winter ones — and the far south gets winter while you get summer.
The straight-up world is fair
Away from the exact poles, our untilted model gives about 12 hours of daylight all year. It ignores atmospheric refraction and the Sun’s apparent size.
The catch: no tilt-driven changes in day length. Other influences, such as orbital distance, are outside this model.
Summer days are long because Earth leans, tipping your half of the planet toward the Sun — so your city spends more of each spin in the light. It's the lean, not how close we are to the Sun.
Psst, grown-ups: Earth's spin axis is tilted about 23.4° and keeps a fixed direction in space as Earth orbits (axial parallelism). Near the June solstice the Northern Hemisphere tips sunward, so the terminator (the day/night line) cuts a northern latitude's daily circle of rotation unequally — most of the circle lies in sunlight, giving more than 12 hours of daylight; above the Arctic Circle the whole circle is lit (the midnight Sun). Day length follows cos H = −tan φ · tan δ, where δ is the Sun's declination. And distance is not the cause: Earth is actually farthest from the Sun (aphelion) in early July, during northern summer — if distance drove it, both hemispheres would have summer at once instead of opposite seasons.