It's not because there's no gravity up there — gravity in space is almost as strong as it is in your bedroom. Astronauts float for a sneakier reason, and once you get it, you'll know a secret most grown-ups don't.
The trick question
Ask most people why astronauts float and they'll say 'no gravity in space'. Here's the secret: that's wrong. The Space Station flies about 400 kilometers up — if you could drive a car straight up, you'd be there in a few hours — and Earth's gravity there is still about 90% as strong as on the ground. If you stood on a tower that tall, you would weigh nearly the same as you do right now. So gravity can't be the answer. Something else is going on.
Falling without landing
Have you ever felt your tummy drop on a big slide or a trampoline? That floaty feeling happens whenever you're falling. Astronauts feel it all the time — because the Station is falling. It's just also moving sideways incredibly fast, about 8 kilometers every second. So as it falls toward Earth, the round Earth curves away underneath it, and it keeps falling and missing, falling and missing, around and around forever. Astronauts float because they're inside a fall that never ends. It even has a proper name: an orbit.
Try it tonight
Here's the best part: you can watch that endless fall with your own eyes. The Station is huge and shiny, and when it passes over your town just after sunset, it looks like a bright star sliding calmly across the sky — no blinking, no sound, taking a few minutes to cross. That dot of light has people inside, floating, maybe eating dinner. Check the tracker on this site to find out where it is right now, and wave. They can't see you — but you'll know their secret.