An ice rainbow appeared at Ted Stevens Anchorage International Airport in Anchorage, Alaska, on January 6, 2020

Ice rainbows are formed by sunlight refracting through ice crystals suspended in the air. It's also called an "optical phenomenon."

Ice rainbows are very rare. They can be seen only when the sun is very high in the sky and the ice crystals in the air have to be hexagonal in shape with their thick plates parallel to the ground.