A Wonderleaf question
How do we know Earth is round?
a real page from the book
We know Earth is round because many independent clues match a curved planet: ships dip from view bottom-first, Earth's shadow on the Moon is always round, and different stars appear as you travel north or south. Satellites and astronauts then checked the same shape directly from space.
One of the clearest proofs used only a stick, sunlight, and geometry. Around 240 BCE, Eratosthenes compared noon shadows in two Egyptian cities and estimated Earth's size surprisingly well, long before cameras, rockets, or weather satellites could show the whole blue curve.
Wonder words
- horizon
- eclipse
- sphere
- orbit
Try it out
At sunset, watch a tall object's shadow stretch, then imagine measuring Earth with shadows and a few careful steps.
Read the whole picture book
Watercolour scenes, straight answers, about three minutes cover to cover.
Open the picture bookOne more wonder: Why is space so dark?
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