Q: What is a lunar rainbow?

A: "It's a rainbow that has been formed by moonlight instead of sunlight," says Brent McRoberts of Texas A&M University. "A lunar rainbow is sometimes called a moon rainbow, but they're the same thing," he explains. "Lunar rainbows are fairly rare. They are usually whitish in color and occur only during a full moon, and as is the case with a rainbow, the light source must be behind you. Lunar rainbows tend to be much fainter than normal rainbows because our eyes don't see color as well at night, plus moonlight produces less color than sunlight."

Q: Do lunar rainbows occur

A: "Yes," McRoberts adds. "It is said Cumberland Falls in Kentucky produces more lunar rainbows than any place else because the conditions are perfect there with the falling water during full moons," he says. "Also, Yosemite National Park is a frequent producer of lunar rainbows because of the geysers and waterfalls in that area. We know lunar rainbows have been observed for thousands of years, at least since the time of Aristotle."