What metaphors are used in Nightfall by Isaac Asimov?

Asimov describes Saro City as a place "where the spires . . . gleamed bloodily on the horizon." He also portrays Beta, the sun, as "dwarfed and evil," while Lagash itself is shown to be a "cold, horribly bleak world." The two writers describe literally the effects of darkness on the landscape, but they also extend darkness to the level of metaphor, for the darkness without represents a darkness within man which is released by the barren landscape.