A moonbow (also known as a lunar rainbow, lunar bow or white rainbow) is a rainbow produced by light reflected off the surface of the moon rather than from direct sunlight. 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. It is difficult for the human eye to discern colors in a moonbow because the light is usually too faint to excite the cone color receptors in human eyes.