I thought the Nirn being in oblivion thing was Camoran's b.s. Or do you mean something else?
edit: Err, wait.. Oblivion isn't space itself, is it?
Kind of.
http://www.imperial-library.info/content/cosmology
What are planets?
The planets are the gods and the planes of the gods, which is the same thing. That they appear as spherical heavenly bodies is a visual phenomena caused by mortal mental stress. Since each plane(t) is an infinite mass of infinite size, as yet surrounded by the Void of Oblivion, the mortal eye registers them as bubbles within a space. Planets are magical and impossible. The eight planets correspond to the Eight Divines. They are all present on the Dwarven Orrery, along with the mortal planet, Nirn.