Why do astronauts float in space?

Astronauts float because they are falling, not because there is no gravity. At the International Space Station's height Earth's gravity is about 90% as strong as on the ground; the station and crew fall toward Earth while moving sideways fast enough to keep missing it.

What's actually true

Astronauts float because they're falling, not because gravity vanished. At the International Space Station's height, Earth's gravity is still about 90 percent as strong as on the ground. Astronauts float because the station and everyone in it are constantly falling toward Earth while moving sideways so fast that they keep missing it. That endless fall feels like weightlessness.

Takeaway: Orbiting is just falling around the planet fast enough to keep missing it.

Why people believe it

The word 'zero gravity' is used everywhere, from news to films, and it describes how floating feels rather than what is happening. Gravity also seems like something that should fade with distance, and space feels very far away, so people assume it simply switches off. The station is only a few hundred kilometres up, though, much closer to Earth than most people picture, and the floating comes from the continuous free fall of orbit.

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