Mother Nature has the ability to create masterpieces in both the sky and on land, and the way that the different features of Earth lay against each other is more than breathtaking. Add the sun to any of her natural creations and its beauty will magnify. We’ve all seen the sun rise and set, and even if it was just in our hometown, the intensity of colors the sun creates easily takes your breath away. Now imagine seeing two more suns in the sky, one on each side of the sun. No, it is not impossible; it is a natural phenomenon known as a sun dog, and it is one of the most beautiful things that I have ever seen.
Also known as mock suns or parhelia, sun dogs are two brightly colored spots that appear next to the sun on each side. They look much like a comet or the sun and are often mistaken for one or the other. They are caused by a reflection or refraction of the sun’s light and are most common when the sun is low on the horizon and ice crystals creating cirrus or cirrostratus clouds are abundant in the atmosphere. So sunrise and sunset of the winter months is the easiest time to view them.
To create sun dogs, rays from the sun are reflected or refracted by atmospheric ice crystals. The ice crystals needed to create this phenomenon are hexagonal and usually larger than 30 micrometers. The flat face of the ice crystal must be horizontally aligned with the horizon. The sunlight then hits the crystal and bends it twenty-two degrees. With this bend, it is then reflected or refracted back into the atmosphere, which creates the illusion of another sun on the twenty-two degree arc. As the sun rises higher in the sky, the sun dogs typically move farther away from the sun and begin to fade until they disappear when the sun reaches sixty-one degrees over the horizon.
The angle of the sun’s rays and the orientation of the crystals do have an impact on the sun dogs. If the sun’s rays are reflected off the ice crystals, or reflected off water and then refocused on the sky above it, the sun dogs will be white. However, if the rays are refracted through the ice crystals, the sun dogs will display a variety of colors, similar to a rainbow. Often, they are red on the side closest to the sun and fade to a bluish color on the side away from the sun.
Sun dogs have been appearing probably since the beginning of time, since all they need are the sun and ice crystals. Throughout history, they have been seen and recorded by people all over the world. Even the Ancient Egyptians have writings that describe two suns, a sun setting in the East, and the possibility of a sun traveling backwards. All of these writings more than likely are describing sun dogs that they Ancient Egyptians have witnessed. Aristotle has also written about sun dogs. He wrote that “two mock suns rose with the sun and followed it all through the day until sunset.” The Ancient Greeks also believed that sun dogs predicted rain. Today we know this to be true because the ice crystals that form them are part of clouds that bring rain.
On April 20, 1535, sun dogs were also visible in the Stockholm sky. For two hours, Swedes witnessed white circles and arcs filling the sky and crossing paths while additional suns also appeared. At the time it was believed to be a sign of God saying that he was coming to seek revenge on King Gustav Vasa, who had just introduced Protestantism.
Believe it or not, sun dogs are visible all over the world at any time of the year, and they are common in Europe and North America. The problem is that no one spends the time looking for them. On average, they occur twice a week on these two continents. The moon also has the same phenomenon, although it is called moon dogs. These are less often seen because most people are sleeping when the moon is in the sky. So spend some time looking at the sky, during night or day, and enjoy the beauty of Mother Nature for free.