Re: If the Moon were replaced by other planets...
anything larger than the Earth would in turn make the Earth its moon.
If Earth and another body were roughly
similar in mass (even one a little greater than the other), the barycenter might be somewhere in open space between them. The two might then orbit around each other like bolas, riding a common orbit around the Sun.
"No, I better not look. I just might be in there."
—Foghorn Leghorn, Little Boy Boo