Weird circle around the sun

[macoman]

I took this photo a week ago and found it interesting.

 

[Ansia]

That is the halo effect. If you see that with the naked eye while looking at an artificial light, you need glasses.

 

[Tufargon]

I see that around the moon all the time around here.

 

[MTPro]

Upper atmosphere ice crystals. Notice the rainbow color effect on the edges.

 

[Goober]

Lots of neat stuff to see in the sky.
This is my go-to site, Atmospheric Optics - Halos for great explanations and pictures.