Corona

Corona is a kind of iridescence, organized in a sequence of colorful, concentric rings around the sun or moon. Reddish colors always occupy the outside of the corona.

It is produced by the diffraction of sunlight or moonlight by individual water droplets (and sometimes tiny ice crystals). Corona size depends on the diameter of cloud droplets, and small droplets produce brighter coronas.

Coronas differ from halos in that they are formed by refraction (rather than diffraction) with relatively large ice crystals rather than small ice crystals, and coronas are much smaller than halos.

The corona should not be confused with the outer atmosphere of the sun, which is seen in total eclipses as it has the same name.