This 22-degree lunar halo was created as light from the full Moon passed through hexagonal-shaped ice crystals within a cirrostratus cloud. The pencil-shaped ice crystals act like prisms and refract, (bend), the moonlight by an angle of 22 degrees. Since blue wavelengths of light are refracted by a greater degree than than red wavelengths of light, the halo's inner edge, (the one closer to the Moon), has a pale reddish orange hue, while the halo's outer perimeter is more of a pale greenish blue. Unlike the brilliant colors seen in a daytime halo around the Sun, those in lunar halos are much less intense to the eyes.