Seeing a rainbow is a stroke of luck, and a double rainbow is even more spectacular. But a triple rainbow? Impossible as it may seem, a bizarre tangling of colorful arcs was sighted in Robbinston, Maine, last week.
Meaghan Callahan Kellenberger snapped this remarkable photo shortly after sunrise. Showers streamed northwest, marking the perfect backdrop for a sun low on the southeast horizon.
Sunlight is the combination of light spanning the color spectrum. But when the sun’s rays shine through a raindrop, that light is forced to slow down. Each color is refracted, or bent, a different amount depending on its speed. The resulting light is separated into individual colors.
A double rainbow results when a fraction of the light exiting the raindrop instead bounces off the droplet’s inner wall. This reflection — and subsequent refraction — causes a dimmer rainbow to appear overhead, thanks to the fainter light. In the second rainbow, the order of the colors is reversed.