Kids ask a lot of questions. mental_floss has answers. WHY?, our new series for kids and parents, tackles all types of questions children have about how the world works by providing science-based, kid-friendly content. Our answers are written with early readers (ages 4 to 7) in mind, but we think they're interesting—and educational—for everyone.
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Believe it or not, even when you’re sitting still in a chair, you’re always moving. That’s because the Earth itself is always moving—and fast! At the equator (ee-KWAY-tor), an invisible line that wraps around the middle of the Earth, the planet is actually spinning at about 1000 miles per hour. That’s almost twice as fast as most planes!
Picture yourself in the back seat of a car driving on a highway. Do you feel like you're moving? No! Now look out the window of this car. You can see the world zipping by … but you feel still. You can't feel it because you and the car are moving together at the same speed. The same thing happens with the Earth. You (and I) are moving at the same speed as the Earth, so we can't feel it move.
Everything in the universe rotates on its own axis, which is an invisible straight line that runs through an object from one end to the other. We call our ends the North Pole and the South Pole. Earth rotates around this axis, just like a spinning top. It takes 24 hours to rotate one time. One rotation equals one day! Every morning when you wake up, the Earth is in the very same place. It starts a whole new spin as you start a brand new day.
The Earth travels at a constant rate, which means it doesn’t speed up or slow down like a car does. Just like with the car window, we can only tell we’re spinning because we can see the Moon orbit around us, and what seems to be the movement of the Sun and stars. (Really, they move too slowly for us to see.) If Earth were suddenly to change speeds, we would feel a really big jolt. It would be like a driver slamming on the car brakes.
For more about the rotation of the Earth, navigate over to NASA's Space Place.