Need help with a 'different' cosmology

I am working on building a world for a fantasy setting. I would like to make it as complete and comprehensive as I can. My biggest problem at the moment is cosmology. I know that I want the solar system to include thirteen planets. I am considering a binary star system. I am interested in making the actual world be a moon of one of the largest planets in the solar system. The planet's placement would be equivalent to Earth's in our system. It would also have sever other moons rotating around it.

My questions are how would all of this affect days [I was thinking of a 36 hour day], months and years? What about the metaphysics of the world, how might that be effected?

Is this a good idea? Bad? Should I just use a planet and not the moon as the world? Would just using the Earth be an even better idea?

I could really use some help and advice with this.

Thanks.

Wait, do you mean physics? Because isn't metaphysics getting into the spiritual stuff?

Anyway, the questions I would think are most important is how big is this moon and the planet it revolves around? Is this planet a gas giant or what? Does it revolve around the planet like our real moon does, and how long does this take? How does this affect sunlight getting to the moon, because that's what's going to determine how many hours are in your day now? How do these other moons affect your inhabited one? Because that's a lot of objects to have affecting the gravitational pull. Basically, you quite probably need less objects within each other's influence. Because the gravity of the moons greatly affects things like tides.

It seems like you're setting up something that's overly complicated unless you know at least the basics of how the physics works. If not, it may just be simplest for you to use an actual planet. Of course, you have said this is a fantasy setting, so you could probably get away with fudging some of these things so long as you're consistent once you make a decision. And, as this is a fantasy setting, I don't think you need to use Earth.

edited 6th Oct '10 11:24:58 PM by AceofSpades

There is no reason that a moon must rotate slower than the Earth, though the most likely outcome would be that it becomes tidally locked to the planet, so that a "month" and "day" are the same length. The physics wouldn't be affected that much, although Jupiter offers examples to the contrary. For instance, Io's surface is kept molten due to its magnetic interactions with Jupiter.

Though, IIRC, there are very few close (Goldilocks zone-close), stable orbits in a binary star system, so it's possible that this is all moot from a scientific standpoint anyway.