What is the symbolic role of the Green Sun in the narrator's visions?

The Green Sun initially appears to the narrator as a 'single, great star, of vivid green' ^[1] that grows to 'vast proportions' ^[1], filling 'all the sky' ^[1]. It is described as a 'huge emerald, scintillating rays of fire across the world' ^[1], and its light is so tremendous that it appears to fill the sky with 'quivering flames' ^[1].

Symbolically, the narrator speculates that this 'stupendous globe of green fire might not be the vast Central Sun—the great sun, 'round which our universe and countless others revolve' ^[1]. He also questions if 'the dead stars make the Green Sun their grave' ^[1] and if it is 'the abode of some vast Intelligence' ^[1]. It represents a source of ultimate light and a potential cosmic center at the end of all things.