A halo is produced by sun light interacting with hexagonal ice crystals suspended in the atmosphere.

The shape of halo depends on crystal type. A ray of light is refracted not only throughneedle-shaped crystals, but also through larger ones called columns that give rise to unusual shapes of halo. Thus light refracting through column-shaped crystals provides “light pillars” and “tangential arcs;” hexagonal plates provoke mock suns, circumzenithal arcs and parhelic circles. In ancient times people considered sun pillars as presages of coming disaster because some of them look like swords.

Halo also appears at night. It is light around the Moon, which is less bright than day time halo and is not split into spectrum but also very beautiful! This phenomenon is called paraselene.

“There is one more optical phenomenon, which impressed ancient people. A Brocken spectre or glory is a shadow, which isvisible on clouds opposite the sun. Is often observed on mountain peaks or while flying at an airplane having a source of light behind. Despite of halo it was a good omen,” said Ms. Matyukhina.

Not only inhabitants of the Earth can enjoy halo. It is proved that it exists in the atmospheres of Jupiter, Mars and Saturn but it differs from Earth`s halos due to various environmental conditions. 

This phenomenon has various forms. Most of them are not researched thoroughly, other ones are not even pictured.