Sun dogs as they are referred to, appear on both sides of the sun when the sun is relatively low and near the horizon. The actual sun and the two images of the same which can be seen can be compared to the Lion, the Wardrobe and the Witch. And it definitely looks much cooler than a rainbow.
Exactly what makes this phenomenon happen? It can be credited to one of the most perfect shapes in the universe, the Hexagon. This phenomenon occurs because of the ice crystals which form in the atmosphere. The ice crystals which form initially in the atmosphere are formed hexagonal in shape. When it becomes sufficiently cold in the air near the ground, these hexagonal crystals of ice fall to the ground and the air above it. This hexagonal shape causes sun beams to scatter in a specific way which causes the appearance of sun in three different places at the same time.