Ancients interpreted such ghostly lights in the sky as signs of something extraordinary. We find only momentary interest, possibly with an understanding this is caused by sunlight refracted by ice crystals in the atmosphere. Still a sense of wonder exists, even if you've seen this before, even if you understand the cause. Why is that? Is it because it's a relatively rare sight? I see it two or three times a year, not so rare. And not nearly as impressive as a full, well defined rainbow.
I think we want to see meaning in any out-of-the-ordinary event. We want to see a sign, a symbol, perhaps a communication. The drive to find a meaning, a story, is an important part of who we are when we have the time and occasion to stop for a moment, think about where we are, and what is around us.
Though we can catch such moments at any time--driving to work, turning to find the source of an unknown sound, catching a moment of quiet on a slow afternoon--the garden's a particularly good place for that.