For proof to me that he appears before heavenly angels as a sun and before spiritual angels as a moon, the Lord in his divine mercy opened my inner eyes to look all the way into heaven. There I saw clearly a radiant moon ringed by many smaller moonlets, whose combined light was almost as strong as the sun’s. As Isaiah said, “The light of the moon will be like the light of the sun” (Isaiah 30:26). But a sight of the sun was not given to me. The moon appeared out in front, toward the right.
Amazing sights can be seen by the Lord’s light in heaven—so many of them that they could never be listed. These sights consist of one scene after another representing the Lord and his kingdom, resembling scenes described by the prophets and by John in the Book of Revelation. There are other symbolic objects as well. We cannot possibly see them with our physical eyes, but as soon as the Lord opens our inner eyes—the eyes of our spirit—similar sights can immediately present themselves to view. The visions of the prophets were nothing more than the opening of their inner eyes. This is what happened when John saw the golden lampstands (Revelation 1:12, 13), the holy city as pure gold, and its light source like a very precious stone (Revelation 21:2, 10, [11, 18]), not to mention much in the prophets. These considerations teach not only that angels live in the highest light but also that heaven contains countless marvels that no one could ever believe.
from Secrets of Heaven, Volume 2, Sections 1531, 1532