Well crap... Why did they have to make that part of the lore so... impossable.
And I looked at the orrery but there was only one planet with 2 moons, but the smaller moon circled the bigger moon... So that didnt make sence. Which one is it, the center? But that has 3... im confused!
So there really is no "size" of anything? So im better off just guessing at thier size and position?
It isnt impossible. Just very difficult for human brains to handle.
Best method is to think in mathematical abstraction terms.
One can have one infinity, containing two (or more) distinct infinities.
For example, we could say that the "space" associated with the sea of oblivion is equivalent to the sum of all real integers.
Inside this now mathematically bounded infinity, you can define other infinities, such as "All real numbers that are equally divisible by 3."
The greater infinity of all real integers can be contained within an even greater infinity, such as "the sum of all numbers, real and imaginary." All of these sets are truly infinite, but it is quite evident that one infinity can be both larger, and even contain another.
[Cosmology] asserts that these interrelated infinities appear as spherical bubbles to mortal minds, because the true conception of one infinity enveloping another is very difficult if not impossible for mortals.
Plane(t)s in the TES universe are similar, except they transcend simple mathematical descriptors. The relationships between them are however, anologous.