How do we know Earth is round?
Round World Clues
How do we know Earth is round?
You're standing on the ground right now, and it feels completely flat. The floor doesn't curve under your feet. The horizon looks like a straight line. So how does anyone know the Earth is actually round — like a giant ball spinning through space?
Here's the first clue: when a ship sails away from shore, it doesn't just get smaller and smaller until it's a tiny dot. Instead, the bottom of the ship disappears first — the hull vanishes below the horizon while the sails are still visible. Then the sails sink down too, like the whole ship is sliding behind a curve. If the Earth were flat, you'd see the entire ship shrinking evenly until it was too small to see.
