Sun dog over Los Alamos, NM
© Sandra Chavez
Daily Postcard: A sun dog is spotted in the sky Wednesday evening above Los Alamos.

According to, a sun dog, or mock Sun, is a concentrated patch of sunlight occasionally seen about 22° to the left or right of the Sun.

Sun dogs often form when sunlight refracts through icy clouds containing hexagonal plate crystals aligned with their large, flat faces parallel to the ground.

Technically known as perihelia (singular parhelion) they are often white but sometimes quite colorful, looking like detached pieces of rainbow, with red on the inside, toward the Sun, and blue on the outside.