A moonbow (or a lunar rainbow) is a rainbow produced by moonlight reflected from droplets of water.
Compared with daytime rainbows, moonbows are relatively faint, due to the smaller amount of light reflected from the surface of the moon. They form in the opposite part of the sky from the moon.
Yosemite National Park is one of the greatest places in the world to see a moonbow thanks to the park’s spectacular waterfalls. One of those waterfalls, Yosemite Falls, is famous for its rare moonbows.
Filmmaker Steven M. Bumgardner produced a short film about this rare phenomena in Yosemite National Park.