A parhelion (or Sun dog) is a halo caused by the refraction of sunlight by ice crystals in the atmosphere. A parhelion typically appears as a pair of subtly colored patches of light, around 22° to the left and right of the Sun, and at the same altitude above the horizon as the Sun. A parhelion is best seen when the Sun is near the horizon. In this case, it was during the midnight sun in the Ross sea. The pancake ice - one of the first stages of formation of new sea ice - that floats on the ocean swell shows how cold that night was.