A sun dog, also known by its scientific name parhelion, meaning “beside the Sun” in Greek, is a fascinating atmospheric phenomenon caused by the refraction of sunlight through ice crystals in high altitude cirrus or cirrostratus clouds. These flat, hexagonal ice crystals act like tiny prisms, bending sunlight as it passes through them and forming bright spots of light on either side of the Sun. Sun dogs typically appear along a 22 degree halo at the same altitude as the Sun and are usually visible when the Sun is low on the horizon, such as during sunrise or sunset. The effect can sometimes be quite dramatic, with the sun dogs glowing brightly and displaying faint rainbow like colors, with red closest to the Sun and blue on the outer edge.

Sun dogs are part of a larger family of ice crystal halos and they often occur in pairs, one on each side of the Sun, though depending on atmospheric conditions sometimes only one is visible. While they may look like small fragments of a rainbow, their formation and positioning are quite different. Unlike rainbows, which are centered around the antisolar point, sun dogs stay aligned horizontally with the Sun, making them seem as though they are flanking it like celestial companions. These beautiful and sometimes ethereal lights are not just captivating to see but also a reminder of the complex and delicate interplay between sunlight and the upper atmosphere.

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