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Not what you think

Why Do Astronauts Float?

There is plenty of gravity up there. They float because they are falling.

Everyone assumes There is no gravity upthereActually Gravity is nearly asstrong as on the ground
They are not beyond gravity. They are falling in it.

  1. Step 1 of 5

    Gravity does not stop at the sky.

    On the ground100% gravitySpace station, 400 km upabout 90%The Moon's distancestill not zero

    The space station orbits 400 km up. Gravity there is still about 90% as strong as it is at your feet. Something else must explain the floating.

  2. Step 2 of 5

    Falling makes weight disappear.

    Standing stillGravity pullsFloor pushes back — you feel weight

    Weight is the feeling of the floor pushing up at you. Take the floor away and let everything fall together, and that pressing feeling vanishes.

  3. Step 3 of 5

    The station is falling — it just keeps missing.

    1 Movingsideways, fast2 Gravity bendsthe path3 Falls aroundthe planet

    It races sideways at about 28,000 km per hour. Gravity keeps bending its path downward, and the ground keeps curving away underneath. It falls forever without landing.

  4. Step 4 of 5

    The astronaut falls at exactly the same rate.

    A dropped lift You'd float inside —brieflyThe space station Same feeling, but itnever lands

    The astronaut, the station, and the sandwich in their hand are all falling together at the same speed. Nothing pushes on anything, so everything floats.

  5. Step 5 of 5

    The right name is free fall.

    Gravity: still strongFloor pushing back:goneEverything fallstogetherResult: floating

    Scientists avoid saying zero gravity. The correct phrase is free fall, or microgravity — because gravity is very much still there, doing all the work.

    Pilots recreate this in a plane that dives steeply. Everyone inside floats for about 25 seconds.

The short version

Astronauts float because they are in free fall, not because gravity has run out.

Try it yourself

Drop a bottle with a hole in the side. Water stops squirting out while it falls — inside, it is weightless too.

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