If you want to stay true to physics then I would go with other planets and 2 moons. If you want to let magic rule the day, then I would talk about a "magical gravity" that allows the moons to "dance about one another" as the orbit the planet. If the moons are essentially orbiting each other as they orbit the planet that would give a lot of explanation about relationships and such and you can explain that the magics involved are what prevents the real physics from tearing the planet apart. Of course you wouldn't want to anger the gods because they might do just that.:o
Well, when the planets align with these 4 "poles" then poo happens - that's the very basic theory, but as with every theory there are 1001 differenent things that can influence the idea
Assuming that the moons are not all precisely alike and spaced equally then they would pass each other in their orbits. I always thought that once you had more than 2 of these object (presumably one being the main planet) then you have the classic "N-body problem" which I thought was impossible to calculate. Now I must be mistaken cos NASA go around making grand statements about Saturn and Jupiter so is anyone able to flesh out a bit how they can do it. Or is it their best guess via a super computer thrashing out a numeric simulation. Wasn't it true for example that they stated that some of Saturns moons in its ring system actually swap over orbits when they get close enough to interact ?
My opinion is to the tune of "Hey theres 5 moons - got it, oh before anyone says to the contrary, theres no silly tides cos as DM I say so." and go with that approach. Its much easier than buying a super computer. :)
Getting deeper and deeper - what was it that Status Quo sang - "down down deeper and down?" :o
It must be possible as the Jovian planets (Gas Giants) all have many moons, but at very different orbits. With different orbits come different sidereal periods (length of time to orbit the main planet). This means that every once in a while there will be an occasion where all, or at least many of the moons are on one side of the planet. This would have a catastrophic effect on the tidal system as the gravitational pull of, as you are using 8 moons we'll go with that. If you had 6+ moons on one side of the planet, then unless you had magnificently high mountainous regions, then that side of the planet would be awash with the seas.
This may influence you planet's design. In the case of the gas giants, it doesn't matter so much as they are so far away from the sun so the majority of planet is frozen gas, with the outer "shell" of the planet being ... liquid then gaseous gas (?). (Assumptions borne out by information sent back from probes, Cassini et al). But your world would be relatively more landed than oceanic in order to prevent civilizations getting obliterated every so often.
Many body problems - well there are many things that could influence a moon or planets orbit. meteors or passing comets are two possibilities that spring immediately to mind. There is a theory that the moon was the result of meteor strike on a newly forming planet earth, the Chicxulub Crater and pacific are two well thought of hypothesis. The scar left by such an impact would still be around.
At the end of the day, I doubt players would question any decision you make too closely, as long as it's not too far off the wall. I mean - have you ever heard anyone questioning the non-effect of the (invisible) black moon in the world of Dragonlance? (It's name escapes me - Lunitari, is one of them - anyway back to the point). I haven't heard of anyone even raising it as a point for discussion, let alone questioning it. And that was a professional published campaign.
YOu guys are a big boost to my pride here, thanks! I think I'll stick with the 8 moons thing...I'll make them all kinda far away from the planet for sure...I'll put some thought into it.
Well, the whole moon planet alignment thing could actually be a great story arc. Perhaps some type of prophesy deal with the seas rising up. perhaps the PC's can actually find some magic item that will stave off certain destruction.
See, now you're talking!
See I have the ruins of an ancient civilization spread all over the world...Perhaps one of their temples contains a magical stone that keeps the moons in perfect alignment. Too cliche? Maybe I need to pay a visit to plotstormers.