I am of the opinion that spheres should be influenced by their respective god's actions. If a god constantly strives to be close to Galbar's sphere, but his own sphere is a celestial one, the sphere itself magically descends down and closer to Galbar, as if answering to its god's wishes.

This can potentially bring about a dynamic relationship between the Gods that came about later on, or that have spheres in the upper realms but want to have more influence over Galbar, and the Gods that are already closer to Galbar and want to retain their position of power there.