Only recently have scientists begun to understand one of the most intimate relationships in the natural world, an almost parental bond between the heavens’ light and the human beings it illuminates. The sky actually seems to understand our need for physical cues that ensure our internal rhythms, and delivers them with an almost limitless subtlety. Minute changes in warmth and color are like a hand on your shoulder that lifts your mood or a subtle prod that corrects the direction of your day.