did you know astronauts float because they keep falling?

astronauts in low Earth orbit float because they and their spacecraft are in continuous free fall together. gravity is still strong there. the floor simply does not have to push up against them as it does on Earth.

it is moving sideways fast enough that, as it falls, Earth's surface curves away beneath it. an orbit is a path continuously bent by gravity, not a place beyond gravity's reach.

standing on Earth, you feel the floor supporting your body. in orbit, your body and the cabin accelerate together under gravity. you do not settle against a floor, so ordinary sensations of weight largely disappear.

small disturbances remain, including drag, spacecraft motion, and gravitational differences across the vehicle. that is why the environment is often called microgravity.

using a spherical Earth with radius about 6,371 km, gravity at 400 km altitude is about (6,371/6,771)² of its surface value: roughly 89%.

g at altitude / g at surface = [R / (R + h)]² ≈ 0.89 at h = 400 km

• acceleration can make a floor push on you. a rotating habitat can also supply a supporting force as it continually changes your direction.
• an orbit is not powered by constant upward thrust. engines change the orbit; gravity supplies the continuous inward acceleration.