While working on the cosmos of a flat world, I came upon the idea of using a dim sum rotating about an axis through the central pole (as described here) in order to accomplish days and seasons. The sun would rotate around the pole of the world with a 1 year period, and a moon would rotate closer to the plane of the world with a larger orbital radius and an orbital period of one day. In this way, night is formed by the umbra of the moon passing over the world as it eclipses the sun, and seasons are formed by the physical distance from the sun to the plane of the earth. However, when trying to work out the orbital periods I realized that the angle from a point to the sun varies over the course of the year, which might impact the required course for the moon to keep up the daily eclipse. Under what conditions would this world receive earth-like brightness during the day over the course of the year (and seasonal temperature variations) but still get 12-hour lunar eclipses for nights, every 12 hours? Is it only possible for a particular sector of the world to receive earth-like cycles, and other parts of the world will simply be exposed to some extreme conditions? Adverse effects of gravity due to the proximity of the bodies can be handwaved away, as this is a flat world.

  • 2
    $\begingroup$ If you are using a spotlight sun then there is no need for a moon to cast a shadow to form the night. Night is where the spotlight sun is not shining. Why do you need two night forming mechanisms? Am I missing something? $\endgroup$
    – Slarty
    Commented Oct 26, 2019 at 11:30
  • $\begingroup$ @Slarty ah maybe I’ve misunderstood spotlight suns then. I mean that the sun is not so bright that it would sear the world to a crisp at the elevation needed to keep up a noticeable circular rotation $\endgroup$
    – whlk
    Commented Oct 27, 2019 at 5:01
  • $\begingroup$ How about earlier precepts of the universe? The sky is a dome, the sun is dragged over it every 24 hours. The moon is dragged less often, and the wanderers (planets) walk forth and back again as they wish. Every thing beyond the sky is unknowable. Unless you have an ultra modern society with an advanced theory of physics. In which case you will probably need two theories, what happens here, and what happens out there. Not unlike our current relativity theory, and quantum mechanics. A theory about normal and large sizes, and a theory about the really tiny things. $\endgroup$
    – Kain0_0
    Commented Oct 28, 2019 at 5:54
  • $\begingroup$ One problem. With a flat world, and assuming it isn't ginormous, wouldn't the sun and moon get flung out of orbit? It is likely the flat planet doesn't have a strong gravitational pull because it isn't nearly as dense in matter as the sun or moon. Therefore, wouldn't this planet either be pulled into a collision course with one, rotate around the moon or sun, or the moon and sun never fully actually start rotating? $\endgroup$
    – A Writer
    Commented Nov 2, 2019 at 15:58
  • $\begingroup$ @Kain0_0 I can’t quite say I understand. Do you mean to ask whether I don’t just use an ancient model and handwave the inconsistencies? $\endgroup$
    – whlk
    Commented Nov 5, 2019 at 20:28

1 Answer 1


I don't mean to be obvious but there are flat earth theorists who have theories on this in the real world.

The way I understand it is that basically the sun is a spotlight and points at different parts of the earth at different times, the moon and stars are points on a black background that move in odd ways and I am not sure how they explain seasons.
I would suggest that you research that stuff to get some kind of scientific logic in a flat world scenario.

I just want to point out that I do not believe in this crap, I have an uncle who does and will not shut up about it. The reason I mention it is that they have, at least, semi-plausible explanations for inconsistencies.

The biggest problem I see for a flat planet is the gravity of the planet itself, there is a vsauce video on youtube which explains this here:


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .