Sun Dogs: Why Does the Sun Have 'Twins'?

On very cold days, water vapor high in the atmosphere freezes into tiny, flat, six-sided ice crystals. These crystals act like millions of tiny glass prisms floating in the air. As they fall slowly through the sky, they act like falling leaves, staying mostly flat and horizontal.

When sunlight hits the sides of these flat ice crystals, the light is bent at an angle of exactly 22 degrees. This bending of light creates two bright 'mock suns' on either side of the real sun, often looking like rainbows that have been stretched out vertically.

The scientific name for a sun dog is 'parhelion.' They always appear at the same height as the sun. Because red light bends less than blue light, the edge of the sun dog closest to the sun usually looks red, while the edges further away look blue or white.