Lunar Double
Rainbow!
An astounding natural
phenomenon that you have probably never seen before: a double lunar
rainbow, or moonbow, arcs over the Pacific Ocean in this photograph by Dr. Dale
Cruikshank. This amazing panorama was taken
from Kaanapali, Maui at 9:30 PM on Feb. 26, 2013.
Rainbows
form when water droplets refract sunlight into its component colors. The same
principle applies to lunar rainbows , but instead of using direct sunlight,
moonbows form when reflected sunlight from the moon is refracted by atmospheric
moisture.
A moonbow
is also known as a lunar rainbow, white rainbow, lunar bow, or space rainbow.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.
Source:
NASA/Dale Cruikshank
Soderman/NLSI Staff
lunarscience.nasa.gov
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