Book 2, Question 135
Why Is Earth Round?
Earth looks flat when you stand on it, but it is really a giant ball. Gravity pulled it into a ball! Gravity pulls every bit of a big planet toward the center.
From the book
Page from A Million Whys Book 2
More fun facts
- Around 350 BC, the Greek thinker Aristotle declared that Earth was a sphere.
- The curved shadow of Earth on the Moon during a lunar eclipse was used as evidence that Earth is round.
- Long ago, people noticed ships' masts disappearing over the horizon and the North Star changing height as they traveled. Both are clues to a round Earth.
- Over 2,000 years ago, Eratosthenes worked out Earth's size by comparing noon shadows in different places.
- Sailors who traveled around the world went out across one ocean and came home from the other direction.
- In the late 1950s and 1960s, the space age let people see for themselves that Earth is round.
- Earth is the only planet whose English name does not come from Greek or Roman myths. It simply means the ground.
Sources: NASA, NASA, NASA, NASA Science
Questions kids ask
Is Earth the biggest rocky planet?
Yes. Earth is the largest of the four rocky planets closest to the Sun, just slightly bigger than Venus.