A moonbow (also known as a lunar rainbow, white rainbow, lunar bow, or space rainbow) is a rainbow produced by light reflected off the surface of the moon (rather than from direct sunlight) refracting off of moisture in the air. 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.
Be sure to also check out the video compilation of 162 photos of the 2012 annular eclipse taken by Dr. Dale Cruikshank at the Grand Canyon in Arizona. Dr. Cruikshank is one of the premier astronomers and planetary scientists in the Astrophysics Branch at NASA Ames Research Center, Moffett Field, Calif.
Posted by: Soderman/NLSI Staff
Source: NASA/Dale Cruikshank