One of the entertaining aspects of world-building is developing the physical characteristics of the setting. Usually this involves drawing a map—which is fun in its own right—and deciding about what kind of “natural wonders” might be needed in your world. For instance, in Athron there is a series of chasms on one part of the map that are inhabited by certain nasties. It is a vast, extensive network of chasms that warrant special attention. They stick out (although I have not mentioned them yet in my books—it hasn’t come up yet). Similar wonders can be found in other books like Piers Anthony’s Xanth series which had the Gap Chasm, among other things. Or the multiple moons of Krynn and, if I recall correctly, Pern.
In my world, I, too, have multiple moons. Two, in fact: Silgaren and Neerie. Silgaren is the larger of the two. It is white, or silver, depending upon how the light strikes it, and it is fairly similar to our own moon here on Earth both in size and general features. Neerie, though, is another story. It is a smaller moon, about half the size of the other, and is a brilliant golden in color. It also has, what appears to be, a cracked surface, not unlike the aforementioned chasms above, but larger and more extensive across a clearly visible section of its surface. It is a great topic of debate on Athron for two reasons: 1) the cracks on Neerie’s surface are an enigma. No one can figure out where they came from or what they mean. And since space travel is not in the near future, the cracks are destined to remain an enigma. 2) The color of the moon is the color of gold. Many a sage has speculated that that means the entire moon is composed of gold. In some records it is referred to as “Neerie: The Torment of the Gods.” It is believed that the gods placed a golden moon above the mortal world to torment the greedy with their thoughts of avarice in the night.
A final thought regarding moons. For a while, I was a bit confused by the phases of the moon. But I think I’ve got it figured out now. For a while, I was thinking that the phases of the moon might be dependent upon the size of the moon and its distance from its respective planet. But that’s not the case; it’s just dependent upon the angle between the locations of the moon, the sun, and the planet. If the angle is zero, the moon will be either full, new, or eclipsed (I think). The important thing to remember is that all moons, unless self-luminous, will follow the same phases as ours. New. Waxing. Full. Waning. New. Etc… I had to think about that (I haven’t studied astronomy in quite some time). Unless, of course, you throw in another star. In that case, I have no clue.
Also, the periods of the moons need not be the same. In fact, it’s probably better that they not be. I’m not sure (like I said, my astronomy is very rusty) but an identical period might (and I mean might) imply an identical orbital distance. In other words, an inevitable collision. Of course, in a world where magic is involved, that can be fixed.