eli5 Does gravity act the same for large objects as it does for small objects. So if I were to shrink planet Earth and the moon to say half the size and the distance between them too then would they continue orbiting. Would this also apply if they somehow became much larger?

Question

eli5 Does gravity act the same for large objects as it does for small objects. So if I were to shrink planet Earth and the moon to say half the size and the distance between them too then would they continue orbiting. Would this also apply if they somehow became much larger?

In: 9

Answer 1

What do you mean by “size” and “larger”? Are you talking about radius or mass or both?

Gravity is a function of mass. If you shrunk Earth an the Moon to half their *radii* but kept their masses the same, their orbital dynamics would be the same. If you changed their masses, then their orbital dynamics would change.

Our sun has a radius of about 7000,000km, If you replaced our sun with a black hole with the same mass but a radius of only 1.5km, the planets would continue to orbit the black hole as if nothing had changed, gravitationally speaking.