Quote:
Originally Posted by yusufcam
How does the sun which is comparable in scale to a soccer ball hold the earth (the size of a marble) in gravitational orbit at 200 mtrs?
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If you could arrange for a soccer ball and a marble to be 200 metres apart in space, and contrive to have them with appropriate initial velocities with respect to each other, the marble would indeed orbit the soccer ball.
Let's assume the soccer ball has a mass of 1 kg, and the marble has a mass of 10 grams. For a circular orbit with a radius of 200 metres, the attractive force is 1.7 x 10^(-17) newtons, and the marble needs a tangential velocity of about 0.6 microns per second, and would have an orbital period of 69 years! (At a radius of just 1 metre, the orbital period would be "only" 9 days.)