Sometimes I like to think about the kinds of sci-fantasy cultures that would grow up on worlds with binary stars or trinary stars, where most of the time you’d have two or more shadows. What sort of beliefs would that create? Shadows are often thought to be related to the soul; if the culture believed in a spirit, would it be dualistic? Two souls inhabiting one body, or two parts to a whole? Maybe they’re both watcher spirits, leading you to fruit or folly. When the suns eclipse each other, you’d only see one shadow; what then?
What about on tidally-locked planets where the only habitable space is in the terminator of the shadow–a narrow world of perpetual twilight, bordered by desert and icecaps. If there are no compasses, how are directions determined? What names do they get? Something to do with ice and fire? How are those two ideas treated?
How about on the tidally-locked habitable moons of gas giants? Where one side of the planet will never see the gas giant, and the other will always have it in view? What myths could be created about the gas giant and the sun? Other moons? Rings? What sort of holidays or ceremonies could be planned around the passing shadow of the planetary ring?
What about the rare moons that aren’t tidally locked? How do you determine the calendar? What myths rise with the eclipsing of the sun by the gas giant, glowing like fire with the sun behind it? Would there be different kinds of days and nights? More than just two? Long nights spent in the shadow of the gas giant?
What myths would a culture create on a habitable rogue planet, with no stars for light, perhaps heated by tidal forces between it and a moon.
How about an undersea culture forever bound under the kilometers-thick ice moon like Europa? With no awareness that anything might even exist above the ice? That is where the universe ends: somewhere in the ice.
Some fun food for thought for you fellow worldbuilders.
