Day and Night in Erebus

I just thought of a question, basic enough that it's probably been answered somewhere in the forum, but also basic enough that I couldn't come up with a search specific enough to find it.

Erebus is an infinite plane, so presumably the mechanic by which we are accustomed to day and night, namely the rotation of the Earth (or orbit of the sun around Earth, depending on how you're thinking about it) wouldn't be able to apply. I'm trying to remember how societies which didn't hold to a spherical Earth explained it... but I feel like those mostly still involved a sun-object moving through the celestial orb above the Earth, and that still doesn't really work if you're dealing with an infinite plane. So how does it work in Erebus?

My first dark-fantasy instinct is that day and night are the incarnation of the eternal struggle between Lugus and Esus, but that's ridiculous because, aside from that probably being direct enough that it would violate the compact, I'm sure even Lugus would agree creation isn't much good without night every so often, and in any case that would suggest neither existed before the fall, and I feel like that's not the case.

While we're on astronomically explained phenomena:
I imagine explanation for the stars moving is similar to whatever explanation exists for the sun?
And how about the seasons? I don't think I even ever learned how the societies which didn't hold to a tilted spherical Earth explain that...

I don't remember reading anything about this subject in FFH lore, so I'm gonna hypothesize (make up) something I like the sound of:

Erebus is an infinite plane. The sky however, is not infinite, or is infinite but much smaller than the ground (imagine a smaller u inside of a bigger u, but both of the u's go on forvever. Also, they might not be shaped like u's but actually like mobius strips or something). The sun and moon move in a fixed pattern around the sky because why not? Thus different parts of Erebus are lit up at different times, but the part where FfH is set are all lit up at once. Seasons are the movement of the sun varying across the year.

Source: Intimate personal experience with astronomy.

As an aside; if I remember rightly, the sun might actually be a portal to Lugus' realm. Or maybe I'm confusing the lore with something else.

Maybe the sky is an infinite plane, but the sun, moon, and stars follow a specific track. This would mean that, either large parts of Erebus have an empty sky (I don't like this), or that different parts of Erebus have completely different skys, with different stars, moon(s), and sun(s).

There's the classic fantasy view, that the sun is a chariot of fire drawn across the sky by some guy every day. This is kinda how it works in Lord of the Rings, however there the world started off as flat but not infinite (it became spherical later), unlike Erebus which is flat and infinite, and so the sun could drop down and go underneath and come up the next day.

So...I'm inclined to think it's more like how it works in The Elder Scrolls, that the heavens are all around us and flowing through us, but mortals can't properly perceive them. So the portion of our brains that interprets sensory data does the best it can and tells us it sees stars and planets and things, when really what we're perceiving is the various realms of gods (or the gods themselves).

The sun might really be Lugus, or his heaven, or most likely the precept of light itself. But Lugus was only one of many who created Erebus, and was complemented by Esus (and, ideally, before anyone fell, they'd get on really well and recognise that each other were necessary for the proper functioning of Erebus), which is why we have night.

And maybe it's a phenomenon unique to Erebus and unchangeable. When creating Erebus, Esus still hadn't fallen, and with him and Lugus still having infinite creative powers they could easily have built a day/night cycle together. But then The One took away the creative powers and BAM! Day/night cycle is fixed. Esus might snuff out the sun if he could, but lacks the power to.

As for how it physically works, with a sun going down or coming up over an infinite flat plane, well, it's probably because it is non-euclidean geometry. Really non-euclidean, like really really, like imagine the twistiest hypercube you can, with every surface covered in fractals, then extend it to 5 dimensions, then turn it inside-out. Ceridwen probably designed that part. Even a flat plane of infinite size can become spherical if you twist space-time just right and squint really hard.

Thank you, IronClaymore. I enjoyed that post very much.