Why do astronauts appear weightless in orbit even though gravity is still strong there?

Astronauts in orbit are not outside Earth’s gravity; they are in continuous free fall. The International Space Station orbits at roughly 400 km above Earth, where gravity is still strong, but the station has enough horizontal speed to keep missing Earth as it falls. That state produces microgravity, not zero gravity, which is why objects float inside the station. The sensation of weight comes from the support force of a floor or seat, and in orbit that support force is absent. The phenomenon is the same reason a falling elevator can make people feel briefly weightless.