A halo can visually form around both the sun and the moon. There are many different halo phenomena. The most common appearance is a ring around the sun or moon, which can be seen by the observer about 22° from the sun or moon. In the high atmosphere, low temperatures must prevail so that ice crystals can form, on which these phenomena can occur through refraction and reflection.
If you want to know more about this phenomenon, you can find more information about this phenomenon here:
https://www.meteoros.de/themen/halos
https://www.dwd.de/DE/service/lexikon/Functions/glossar.html?lv3=101154&lv2=101094
