Through His creation God reveals metaphors, allegories of spiritual truth. I speculate that the sun represents God. It's substance and light and heat the Trinity. The moon represents the Christian; dead rock having no light
of its own, but reflecting the light of Christ to a world in darkness. For those who don't know Christ live in darkness. A time will come when God will shine much brighter and the knowledge of God will fill the earth as waters cover the seas. And so also the moon, that is the people of God, will shine as the sun. For we will have been brought to perfection. For "we know that when he appears, we shall be like him, for we shall see him as he is." 1John 3:2

Daniel 12:2,3  Multitudes who sleep in the dust of the earth will awake: some to everlasting life, others to shame and everlasting contempt. Those who are wise will shine like the brightness of the heavens, and those who lead many to righteousness, like the stars for ever and ever.