Lunar rainbow
A lunar rainbow is a rainbow created by the moonlight . Because even the full moon is 470,000 times weaker than the sun, lunar rainbows are faint and difficult to see, especially if they are impaired by light pollution . They appear white to the human eye due to their weakness of light, since no colors are perceived when seeing at night . However, lunar rainbows are also colored in photos taken with a long exposure time or with high light sensitivity (see pictures below).
Lunar rainbows are observed much less often than ordinary rainbows because the brightness of a crescent moon is not sufficient for a lunar rainbow. The brightness is only sufficient at the time of the full moon and on a few nights before or after the full moon.
Caspar David Friedrich : Mountain landscape with rainbow (1810), whether the depiction of a lunar rainbow was intended is controversial.
Lunar rainbow at Lower Yosemite Fall
Lunar rainbow at Victoria Falls in Zimbabwe, 2013
