A question for you brainiacs out there.

[Wippit Guud]

It's strange that nothing in Dragonlance brought up what 3 moons did, or how switching to 1 moon changed anything.

Now, I don't know what they have astromically, but if you read the Song of Ice and Fire series, their seasons are quite different. They're have a periods of 7-10 years of warm summer and warm winter, probably equivalent to what'd you experience in place like South Carolina. Then they have another period of 7-10 years of cold summer and cold winter... think Russia.

Course, even stranger, when the book takes place, it's been the warm season for over 20 years. But it makes a good basis for what weather would be like with two suns if it's an uneven orbit, or even better if the planet actually orbits in between the suns. The 20 years of summer could even be a period when the gravities from the sun almost cancel each other out, slowing the planet down to a crawl in between them.

 

[Dimwhit]

Then there is the concepts of magic. If you assume that the stars or the moons have any influence on level of magic in the world, it could get real interesting. If the second star repesents a specific god, say a chaotic one, and it's followers get more powerful as he gets closer, things could get fun....

Ooo, I like that.

Thanks all for the responses. Sounds like the possiblities are endless. I suppose much of this would be better developed in a novel than a D&D campaign, but I think it could be interesting.

 

[smetzger]

This online program will let you make a campaign calendar, complete with phases of moon. You can select how many moons your world has.

http://www.irony.com/mkcal.html

 

[Zander]

Of course, all the above about multiple suns assumes a Copernican (i.e. heliocentric) system. You could have a Ptolemaic system with the suns orbiting the planet. Or even a combination with one sun heliocentric and the other geocentric - freaky! It's fantasy after all.

 

[DMScott]

A sci-fi gaming staple for physics-friendly multi-sun systems is to have the "planet" be the moon of a gas giant at or near brown dwarf size. A sufficiently massive gas giant can produce enough heat for long enough to allow a large moon to have an ecosphere, even when the gas giant and moons are far outside of a system's normal life zone, so you avoid the usual close binary problems of planets near the stars in unstable orbits. You can get a usable world this way, with really impressive tides and weather. IIRC, both Traveller and 2300 AD had supplements with worlds like this.

I dunno if you really want to get to that kind of scientific detail, though. Seems to me in a fantasy world, it's more important to have a good magical and/or religious treatment of your unique suns and moons than to get the science perfect. I'd just have strong tides and brutally hot summers, and concentrate more effort on special conjunctions and such and how they affect gods/dragons/powerful magic/etc. Definitely need some huge magical/religious implications for double eclipses.

 

[Cybern]

I had the same problem developping my setting for tomorow's game. Mine is somewhat different though:

The world was in chaos, in a everlasting apocalyptic war. The legends of this world said that the gods lived on the moon, and in this world's history they tried to reach it but only wizards did, but never came back. (in my setting the moon is smaller but nearer).

A sage from some other realm (a Githzerai) came to save them. He had the Power of Limbo (to call elements into existence, only better than in the MotP), and started to summon a tower, with stairs and a chain to lift people and stuff up to the moon. The construction took real long, years in fact. As his new followers escaped the wars below by living in the tower, they started to feel bad from lack of air. He then summoned air (and water), but air and water came to the tower from the planet (killing almost every one, except certain species who mutated). The tower eventually reached the moon but broke appart when it made contact. The chain remained in the middle, and as long as she move, there is gravity centered on it.

As the PC enter the world (from FR), the tower fragments are moving islands on cylindrical water world linking the earth and the moon. The great storms at the base of the sea circle the planet, and some "jumpers" have capsules (giant walnuts, really! ) that permits them to haul rocks into the cylinder, making a living. At the other end, the ancient sect guards what is on the moon (not the gods, but some mysterious world I'm still working on). As nature dwindled, the great druids moved the life tree on a km long giant turtle and move to the sea.

Most living creatures live on giant turtles/island, on chunks of the tower etc., and no map is correct as things move. It isn't Water World, as most islands are living and are more numerous than in the movie.

I'm still working on it, but I had problem evaluating the effects of 99.99% of the water and air being sucked from the planet. Could creatures still live (such as insects/plants?). I killed all the underground races, and the marine ones were carried by the water. I have an Air Genasi (mutated) race that lives on the storm, riding it with shield-like sails (and their levitate ability), and undeads all over the earth.

While my setting is not like yours, I agree that moon/sun related issues are hard to implement in these cases. Some brainiacs players will argue that it's impossible, while some won't bother and will enjoy. I guess as long as the players experience the fantasy, no one will care if it's not realistic enough.

Good luck with yours!

 

[Ran]

to have the "planet" be the moon of a gas giant at or near brown dwarf size. A sufficiently massive gas giant can produce enough heat for long enough to allow a large moon to have an ecosphere, even when the gas giant and moons are far outside of a system's normal life zone, so you avoid the usual close binary problems of planets near the stars in unstable orbits. You can get a usable world this way, with really impressive tides and weather.

Hey, I LIKED that!!!!

Would you mind speaking more of it?

 

[Steverooo]

A sci-fi gaming staple for physics-friendly multi-sun systems is to have the "planet" be the moon of a gas giant at or near brown dwarf size. A sufficiently massive gas giant can produce enough heat for long enough to allow a large moon to have an ecosphere, even when the gas giant and moons are far outside of a system's normal life zone, so you avoid the usual close binary problems of planets near the stars in unstable orbits. You can get a usable world this way, with really impressive tides and weather. IIRC, both Traveller and 2300 AD had supplements with worlds like this.

In 2300AD, the world was (IIRC) Aurore, circling the super-Jovian Tithonus (the worlds named after the Greco-Roman Goddess of Spring, and her Human lover, who was granted eternal LIFE, but not eternal YOUTH by the gods, and slowly aged, but never died...) Traveller I wouldn't know about.

 

[Spirus]

What about an earth like planet that is a different size than earth: like one the size of say Mercury or Uranus? How would that effect things?

 

[William Ronald]

Unless a Mercury sized world was truly massive, comprised of a mithral or adamantine core, I doubt it could hold an atmosphere in a fantasy world. On a Mercury-sized world, I could see underground areas that are artificial habitats.

Uranus and the other gas giants are believed to have rocky-metallic cores and possess gravitational fields strong enough to hold relatively light gases such as hydrogen and helium. They are not good candidates for life as we understand it.

It is possible to have Earth-like worlds larger than our own, but I am uncertain at what point such a world would qualify as a gas giant. (It is important to have a breathable atmosphere in a campaign. )