Ring Around the Moon

Cold night but the sky was fairly clear. The moon appeared to have a ring around it. There are two different phenomena. A halo is caused by refraction  when moonlight passes through thin clouds of ice crystals high in Earth's atmosphere. As moonlight passes through the ice crystals, it is bent in a way similar to light passing through a lens. The shape of the ice crystals causes the moonlight to be focused into a ring.

However, this looks more like a corona.  This happens when the light of the Moon, is diffracted on small drops of water in the clouds, so by diffraction of the light and not refraction. A whitish disc with a coloured rim becomes visible.