Did you know that rainbows can be formed by moonlight, as well as by the sun? A moonbow (also known as a lunar rainbow or white rainbow), are much fainter than solar rainbows, due to the smaller amount of light reflected from the surface of the moon.
As physicist Professor Brian Cox explains on this clip from the BBC series Forces of Nature,
“When the sun, moon and earth align, moonlight interacts with the spray at the foot of the falls to form a moonbow. Light leaves the sun, travels 93 million miles across space and reflects off the surface of the moon, and enters the earth’s atmosphere, bounces in and out of water droplets in the waterfall, enters my eye and that sends a signal to my brain, and I reconstruct that signal as something beautiful.”
There are many locations around the world where you can see a moonbow, in places with spray, fog or mist. In the United States, moonbows may be seen at waterfalls in Yosemite National Park, California and Cumberland Falls, near Corbin, Kentucky. Victoria Falls in Africa and Plitvice Lakes in Croatia are also widely known for spray moonbows.