Why do astronauts float in space?

Have you ever hopped down from a step and felt your tummy go light for a moment? For that tiny moment, your feet press on nothing at all. Hold on to that feeling, because it is a clue.

High above us, astronauts live inside a big space station. Their pencils drift through the air, and the astronauts themselves bob gently from wall to wall. So why do astronauts float in space?

Earth pulls everything toward it, from a falling apple to you on your bed. That pull still reaches the space station, almost as strong as down here. Space is not a place without Earth's pull.

So Earth's pull makes the space station fall toward Earth, all the time. The astronauts inside fall too, at exactly the same speed as their station. They and the walls and the floor all drop together.

When you and the floor fall together, the floor cannot push up on your feet. Nothing presses on you, so you float, like your light tummy off that step. But if the station keeps falling, why doesn't it crash into the ground?

The space station also zooms sideways, faster than any jet plane. It goes so fast that while it falls, the round Earth curves away beneath it, so the station keeps missing the ground.

Scientists call this round-and-round falling path an orbit, which means a path that loops all the way around a planet. The station in its orbit keeps falling, yet it never lands.

Every moment of their orbit, the astronauts fall right along with their station. So they float while they work, eat and play. With one soft push of a finger, an astronaut glides across the room.

Let's remember one word: orbit. Earth's pull keeps the astronauts and their station falling together around Earth in an orbit, so nothing presses on their feet and they float.

Next time you hop off a step and your tummy goes light, you can smile and think of the astronauts falling and floating high above you.