Some very observant KVOA viewers captured atmospheric awesomeness on Sunday.
Sun halo over Tucson, AZ
© Shane Gillies
Every so often, Southern Arizona is treated to a huge ring surrounding the sun or moon. So what causes it? Let's explore the world of optics. (I promise to keep it simple.)
Optic diagram of sun haloes
© University of Illinois

Hexagonal ice crystals are typically found in high level clouds like cirrus. These ice crystals refract sunlight or moonlight twice, netting a 22° shift from its original path. The net result is the brilliant 22° halo that catches the eye.

Sun halo over Tucson, AZ
© Jordan Pegram