Flat worlds, toroidal planets, cube planets, etc.
My longest-lasting conworld existed on the inner surface of a sphere with a light source at the center. I briefly considered having Yih (the homeworld of the yinrih) be a toroidal planet, but thought it was too out there and decided to give it a ring instead.
My world is also the inner surface of a sphere with a light in the center. I considered the inside of a torus instead, but decided that would conflict with too many of my other ideas.
My world’s light source is a small sun that revolves once per day and bobs perpendicular to its rotation for summer and winter, up and down once each per year. I also have a second sun outside the sphere on an elliptical orbit, for longer periods of hot (near the planet) and cold (far), mostly to explain how geophysical heating and cooling make the surface expand and shrink to form mountains as an alternative to plate tectonics and volcanoes.
Interesting.
In my case, the light was the physical manifestation of a god of order. Opposing the light was a god of chaos and entropy that appeared as a writhing mass of viscera that completely surrounded the sphere, underground from the perspective of the inhabitants living on the inner surface. The world existed near the birth of the universe or near its end; it’s not clear to the inhabitants which is true. The light is either banishing the chaos and establishing physical laws, or fighting a losing battle against the incarnation of heat death. Magic is possible either because the laws of physics are still sorting themselves out or because they’re breaking down.
A day-night cycle was made possible thanks to a hemispherical shield that orbited the light, occulting it for half a day
That’s neat. My day-night cycle is clouds that form on the side of the world where the sun isn’t. The sun itself is a white hole, so in addition to making light and heat it has a gravitational lens effect so it’s impossible to see the ground on the opposite side of it. I can elaborate on that if it doesn’t make sense.
I’m curious about the white hole. That was something I played around with, that the central light was spewing out matter and had a negative gravitational field that pushed people toward the surface since you don’t experience the gravity of a sphere if you’re inside it.
I’d also like to know more about the clouds.
The clouds are just thick enough to block out sunlight, except on the tallest mountains and some very high flying islands. At the poles (not magnetic poles, but perpendicular to the sun’s rotation) you get months of sunlight or shade in summer or winter, respectively, a bit like Earth’s polar regions and their midnight sun. I haven’t put much thought into the clouds since i had the idea two years and a week ago.
The white hole is one of the things i handwave some details of. I think of it as a black hole moving backward in time, spewing out light and pushing matter away. This relies on the assumption that tachyons have negative mass, and objects with negative mass repel objects with positive mass (or at least attract them while moving backward in time, so it looks like a gravitational push to a forward-time observer). Why it only emits light and nothing else, i don’t know. The point of this is mostly that it acts as a reverse gravitational lens (or “gravitational snel” in my original notes).
Here, an observer (eye) can see an object (star) by looking right at it, or by looking almost straight up at the sun. The object would appear to be smeared across the sky, getting brighter and smaller closer to the sun. In practice it’s not quite that neat, as part of the world is always covered by clouds, and things that are really far away are hard to see in detail. But this is basically how the sky is distorted.