A moonbow, sometimes called a moon rainbow, was detected in Fáskrúðsfjörður, the East Fjords, early Tuesday morning. Jónína Guðrún Óskarsdóttir, a registered nurse, was outside, watching the Northern lights, close to the abandoned farm Brimnesgerði, when the moonbow appeared below the aurora borealis.
Jónína caugt the phenomenon on camera. This was the first time in her life that she saw such a bow. A moonbow differs from a common rainbow in that it is created by the moon, instead of the sun. Moonbeams which bounce in and out of falling raindrops break into their primary colors and form an arc across the sky.
On the website of the Icelandic Met Office, meteorologist Trausti Jónsson explains, “they are the likeliest to form when it’s windy, where the wind carries rain into a clearing, which forms in a cloud cover on the leeward side of a mountain… The rain forms over the mountain range, but it’s windy enough that the drops don’t fall on Earth until 1-3 km from the place they were formed. That gives moonlight the chance to shine onto the collection of drops, which breaks the light and reflects it, as in a regular rainbow, which has the same angle as if it were sunlight, in the opposite direction of the source of light… Chances of seeing a moonbow are the greatest at night if the moon is full and high enough in the sky to appear in the clearance between the clouds.”