Two extra thoughts: (1) Aren't sunsets unique in terms of the configuration/state of the atmosphere between the sun and the observing eye? (2) The "miracle" to me is that sunsets can be such an aesthetic experience. Why are we "wired" that way? I think the simplest explanation is it's a by-product of a survival asset (associating colors with, e.g., what fruits to eat). But could this explanation be inadequate in light of how woven throughout human consciousness and life aesthetic experience is, and how much human activity it generates?