A ring of light is sometimes visible around the sun or moon. When this happens, it s because light is refracted through ice crystals in the atmosphere. Another solar phenomenon is the sundog or mock sun. It also produced by refraction of light through ice crystals. When the sun is near the horizon, a sundog would appear as brightly colored spots on either side of the sun.
Several phenomena are due to diffraction, or light being bent around objects.
A bright ring of light may appear to rest on top of the moon when it is viewed through thin, high clouds. A similar effect is possible with the sun, but because the sun is much brighter, it is more difficult to discern. Iridescence is another diffraction phenomena. It occurs when droplets of different size are present within a cloud. When light passes through layers of the atmosphere that have different densities, objects may appear far from its true position.