Short answer: astronauts in orbit are not beyond Earth's gravity. They appear weightless because the spacecraft and everything inside it are in continuous free fall together.
Falling without hitting the ground
Earth pulls the International Space Station downward, but the station also moves sideways extremely fast. Its path curves downward at roughly the same rate that Earth's surface curves away beneath it. The result is an orbit: constant falling around the planet.
Inside the station, an astronaut, a floating pen and the spacecraft itself all accelerate together. Because the floor is not continuously pushing upward on the astronaut the way a floor does on Earth, the astronaut experiences microgravity and floats relative to the cabin.
“Zero gravity” is convenient language, not the literal physics
NASA notes that Earth's gravity remains strong at the altitude of the space station. Microgravity describes the near-weightless condition produced by free fall, not the absence of gravity.
Quick follow-ups
FAQ
Is there no gravity on the International Space Station?
There is still substantial Earth gravity at ISS altitude. The floating condition comes from continuous free fall.
Why does a dropped object float beside an astronaut?
The object and astronaut are accelerating together, so there is little relative falling motion between them inside the orbiting spacecraft.
Check the evidence
Sources
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