Why is Earth’s gravity strong enough to keep the Moon in orbit but not strong enough to prevent astronauts in space from floating?

Question

Why is Earth’s gravity strong enough to keep the Moon in orbit but not strong enough to prevent astronauts in space from floating?

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Answer 1

Orbiting is constant free-fall where your horizontal speed causes you to miss the ground because it curves away from you as you fall towards it. People writing about this generally aren’t very knowledgeable, and think that the people that they are writing for are dumber than they are, so they describe this constant free-fall as weightless or zero-g. Neither description is accurate. You feel weightless in free-fall since the only normal force is air resistance (inside the atmosphere anyways) when you’re used to feeling the ground push up on you.

In reality, astronauts are not weightless (they have a mass in the presence of a gravitational field) and are not experiencing zero-G on the ISS. The gravitational force in low earth orbit IS a little weaker than on the ground, but those astronauts on the ISS still weigh about 90% of what they do on the ground.