Have you ever seen a little rainbow off to the side of the Sun? Rare but
rewarding to see, such spectacles are known as sundogs, mock suns or
parhelia. Sundogs are just sunlight refracting through hexagonal falling ice crystals in the Earth's atmosphere. When thin ice crystals flitter down nearly horizontally, they best refract sunlight sideways and create sundogs. Alternatively, randomly oriented ice crystals may create a complete circular sun halo. Sundogs occur 22 degrees to each side of a setting or rising Sun, although
sometimes nearby clouds can block one or both. The above image was taken
through a polarizing filter during October 2012 in Mérida, Spain.