Rare but rewarding to see, a little rainbow off to the side of the Sun, 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. Image © Juan Manuel Pérez Rayego
When thin ice crystals flitter down nearly horizontally, they best refract sunlight sideways and create sun dogs. 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.