Strange Phenomena: Moonbow

A moonbow is a rainbow produced by light reflected off the surface of the moon (as opposed to direct sunlight) refracting off of moisture laden clouds in the atmosphere. Moonbows are relatively faint, due to the smaller amount of light reflected from the surface of the moon. They are always in the opposite part of the sky from the moon.

Because the light is usually too faint to excite the cone color receptors in human eyes, it is difficult for the human eye to discern colors in a moonbow. As a result, they often appear to be white. However, the colors in a moonbow do appear in long exposure photographs.