What Makes a ‘Day’ Exactly 24 Hours?

A day is exactly 24 hours because Earth takes that long to make one full turn on its axis.

Imagine you're sitting on a giant spinning chair, that's like being on Earth! When you spin all the way around, you've made one full turn. That’s how we know a day has passed. Now, think of your favorite toy car, it goes round and round on a track. If it takes 24 minutes to go all the way around, that's like Earth taking 24 hours to complete its spin.

Earth’s spin is pretty steady, like how you swing back and forth on a swing at the same speed every time. We've counted how long it takes for us to see the sun come up again after it goes down, and that number has been 24 hours for as long as we’ve been keeping track.

If Earth took 25 hours to spin, our days would be longer, like having an extra minute of playtime every day! But right now, it’s exactly 24 hours, so we can count on our days being just the right length for all our games and naps.