32519, on 2013-October-11, 16:08, said:
This whole science thing is all very confusing.
Isaac Newton figured out that gravity keeps my feet on the ground. But when I leave the earths atmosphere, the law of gravity no longer applies. Suddenly I have become weightless.
"Weightlessness" is an illusion.
When you're on the earth, gravity is pulling you towards the center of the earth. But the solid ground is keeping you from falling in, and you can feel this against your feet. So you can tell that gravity is in effect.
When you're in orbit around the earth, you're also falling. But the spaceship or space station you're on is also falling at the same rate. So nothing is pushing at you against the force of gravity, so you can't feel it.
The Air Force trains astronauts in a jet they call the "vomit comet". It simulates weightlessness in a very simple manner: it goes up and down like a roller coaster. When it goes down, it dives at the same rate of acceleration as gravity, so the passengers "float" in the middle of the cabin. If the jet were flying horizontally at that altitude, you'd feel the gravity, but because it's going down at the same rate as you would fall if there were no plane, you stop feeling it.