Dwimmermount Solar(?) System

Dwimmermount describes the worlds of Ioun (taking the place of Luna in relation to our Earth), Aeron and Kythirea as orbiting Telluria. Effectively, all of these worlds are moons of Telluria, but only Ioun Is close enough to be thought of as "the Moon".

One question I have, does Telluria orbit the sun, or does the sun orbit Telluria?

In the former case it seems that with Aeron and Kytheria being so far from Telluria that they're observed in the practical sense as planets instead of moons that these planets would be affected by wide variances of temperature as they are get significantly closer or farther away from the sun as they orbit Telluria. (Barring the explanation that their climates are more stable due to magic of one kind or another.) Unless their orbits were perpendicular to the orbital plane of Telluria in relation to the sun, and parallel to the sun itself. I'm not sure I'm using the correct terms here, but imagine the line between Telluria and the sun being an axle,nand the orbits of Aeron or Kytheria being a wheel around the "hub" of Telluria that allows the axle to roll 360 degrees around the central point of the sun. It's weird, but it's the only way I've been able to make sense of Aeron and Kytheria also orbiting Telluria.

In the case where the sun also orbits Telluria I haven't been able to come up with any way this would actually make any kind of sense for Aeron and Kytheria to have any stability to their climate outside of super magic.

An exhibit in Dwimmermount also displays representations of planets known as Kron and Diwo. It seems these planets are otherwise unknown to the inhabitants of Telluria. Is there anything else known about these planets? Are these planets otherwise un-observable planets in the Dwimmerount solar system? Former home planets for the Ancients? I'll understand if the answer is "nobody outside of James" knows. Just wondering if there was further available information that I had missed. It seems like the elders to the Terrims living below Dwimmermount might know.

I think it’s supposed to be heliocentric, but that’s just my assumption.

The cosmology is clearly different from ours, and I would assume that distance to the sun had relatively little to do with temperature. You’ll drive yourself crazy if you try to use Newtonian physics here. There’s a magical fluid that conducts the heat of the sun. Filaments carry the heat, making them all equally temperate (or not).

As for the other planets, I think it’s deliberately left open. That said, I assume they’re loosely based on Mercury and Jupiter.

Perhaps Kron is home to a race of metal men powered by the sun. Some crashed on earth a long time ago, drawn by the Dwimmer-beacon.

Perhaps Diwo (Jupiter) is a volcano planet, occupied by vicious skeleton men who have enslaved those who have visited in the past. They are masters of necromancy, and wield technology powered by stolen life force.

I just made those up, but I would suggest looking to “sword and planet” stories for inspiration for your own versions.

I can treat Kron And Diwo as blank slates for now. I guess I didn't miss any other information about them.

In regards to whether or not Telluria orbits the sun or vice versa, I think I'll have to go with a heliocentric model with weird orbits by Aeron and Kytheria around Telluria. I know I could just say "it's magic" and have the sun orbit Telluria, but my players are pretty much sticklers when it comes to matters of astronomy. 

Thanks for the feedback.

Greyhawk used a geocentric model, so there's precedence for it in D&D.