I'm not sure if this question belongs here or over on Physics Stack Exchange.
The Earth and Moon are unique in the Solar System in that the Moon is a significant size compared to the Earth, at 1/4 the diameter and 1/80 the mass.
In the Solar System planets are distributed in an exponential fashion with each being roughly twice the distance from the Sun. (See the Titus-Bode law.) In each case, the attraction of the Sun is by far stronger compared to the attraction of other planets.
A favorite theme of science fiction illustrators is several large moons hanging in the sky. (Sometimes they even get the phases right.)
Is this possible? Can a planet have a stable configuration of multiple moons, each one large enough to provide a visible disk and signficant ground illumination?
For the sake of discussion, let's call the minimum angle one degree (twice the apparent size of the moon.
So we could use a moon twice the diameter of our Moon. This would be eight times as massive. Our average 6-foot tides would be 50-foot tides. Yikes.
We'll call moon #2 Selene. Make it much smaller but much closer. If it was 1/8 the diameter and 1/4 of the distance it would appear half as large and have 1/500 the mass, but tides go as the third power of distance, so it would have a net effect of 1/8 the tide of our Moon. The orbital period would be about 1/4 the length of our Moon's - about a week.
Now, I'm guessing that if were exactly 1/4 of our Moon's period there would be resonance, and everything would come crashing down around my ears. But now I'm stuck. What determines a stable configuration?