Now, I know that the planets that are seen from Nirn are the Aedra, however I'm having trouble understanding which division of the Aurbis they are a part of. They are of infinite mass within the infinite massless Oblivion, however they aren't exactly a part of Oblivion as they have mass. They are separated from Aetherius. From what I understand, the Mundus is the limited balls of matter known as Masser and Secunda in addition to the limited planet Nirn. So, what/where are the Planets? Are they considered a part of Mundus?