Why does an astronaut float on the Moon?

The premise of the question is misleading: in the Apollo mission footage, no one floats. The astronauts are standing on the ground and leave crisp footprints, something impossible without weight. The Moon has far less mass than Earth, and its surface gravity is about 1.62 meters per second squared, roughly a sixth of Earth's 9.81. An astronaut who, suited up with a life-support backpack, weighed around 160 kilograms on Earth weighed there what 27 kilograms would weigh on Earth's surface.

Mass, however, doesn't change. That asymmetry explains the odd movements seen on video: it costs the same effort to start the body moving or to stop it, because inertia is the same as always, but friction with the ground is six times lower because it depends on weight. Walking the way one does on Earth was inefficient, so crews adopted a bounding lope, pushing off with both feet at once, which gave them more control.

A jump lasts longer because the acceleration pulling the body back down is six times smaller. With the same leg push, the height reached is six times greater and the time in the air roughly 2.4 times longer. The eye, used to how things fall on Earth, reads that lazy fall as slow-motion footage. The dust kicked up by the boots adds to the impression too: with no atmosphere to slow or scatter it, each particle traces a clean parabola and falls all at once, without the lingering cloud that would hang in the air on Earth.

That reduced gravity is an advantage for launching and for carrying cargo, but it complicates balance: the rigid suit raises the body's center of gravity, and several falls were caught on camera. Programs planning long stays are studying how a sixth of gravity affects bone and muscle, an intermediate regime between Earth and orbital microgravity for which there's little data.