The phenomenon is called a Lunar Halo or 22° halo where there is an incredible circle around the moon. This happens when there are ice particles in the air around the moon’s surface.
Lunar halos are caused by the refraction, reflection and dispersion of light through ice particles suspended within the thin, wispy, high altitude cirrus or cirrostratus clouds. As lights passes through these hexagon-shaped ice crystal, it is bent at a 22 degree angle (thus the 22° halo), creating a halo 22 degrees in radius.
Did you get that? Me neither. Anyways, although they are beautiful to look at, folklore has been associating the lunar halo to indicate bad weather or strong atmospheric conditions. They are believed to warn of strong rains that are on the way.
Also, legends says if you count the number of stars inside the lunar halo, that’s the number of days before it will rain.
source: scoopboy.com
