A Sun Dog is a bright spot which appears on either side of the sun when it is near the horizon. They are caused by ice crystals in the upper atmosphere which refract light in a certain way. In other words, you have the sun setting on both horizons, the real one in the west and a refraction or reflection of the image in the east. I had to look this up to make sure I had it right. This was taken on the plains of Colorado at the end of a very cold and sunny day in February. Oh, by the way, I also have a photo of the sun setting in the west.