Rare double lunar rainbow spotted in Iceland

Icelandic residents were given a stunning visual treat when a rare lunar rainbow appeared in the night sky last week.

The lunar rainbow, or "moonbow," could be seen just outside the town of Stykkisholmur on Nov. 22, according to Iceland Magazine. Photographer Vioir Bjornsson posted images of the dazzling weather phenomenon to his Instagram page.

"I was driving in heavy rain and so much wind and I just stopped the car because I could not believe what I was seeing, Bjornsson told BBC. "First I thought I was just seeing some reflection from the window of my car, but then me and my friend who was driving decided to stop and try to get a picture of it."

The photographer said that a second rainbow was also visible, although it's difficult to make it out in the photograph. "I have never seen this before," Bjornsson said.

Lunar rainbows are formed the same way regular rainbows are, with the reflection and dispersion of light in water droplets causing a spectrum of colorful light to appear in the sky. The only difference is that for lunar rainbows, the source of light is the moon, not the sun.

Since moonlight is much more dim than sunlight, this makes it difficult to see lunar rainbows, with their colors often looking faint and white, according to Iceland Magazine. Your best bet to see a lunar rainbow is around the time of a full moon, where lunar light is brightest.