Halos like this one around the sun or moon are caused by ice crystal high in Earth's sky. Notice the upside-down rainbow-like arc above. It's called a circumzenithal arc.
© Russ Adams
Russ Adams in Pike County, Illinois caught this beautiful scene on December 22, 2016. The upside-down rainbow-like arc above is called a circumzenithal arc. The circle around the setting sun is called a 22-degree halo, and this halo has two sun dogs, or bright spots, visible on it.

Amazing and beautiful catch, Russ! Thank you.