Sundogs, also known as mock suns, are optical phenomena that occur when sunlight passes through ice crystals in the air. While "sundog" is the commonly used term, there are a few synonyms for the phenomenon. One synonym is "parhelion," a word derived from the Greek for "beside the sun." Another synonym is "phantom sun," which refers to the sun-like image that appears next to the actual sun. "Sunbow" and "icebow" are also used to describe the colorful rings or arcs that form around sundogs. Finally, some people refer to sundogs as "mock moons," as they can also occur around the moon. Regardless of the synonym used, seeing a sundog is always a breathtaking sight.