How can you stay in a plane when it flies 500mph? Just fine, have a nap if you wish. In relation to the plane, you are sitting perfectly stationary, what does it matter how fast the plane is in relation to the ground?
It’s important to understand there is no preferred frame of reference for the universe, speed is always relative between two objects, when you are orbiting a planet, then your speed in relation to the planet is all that matters. What is your speed in relation to other planets, stars or galaxies, is not relevant.
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