A sun dog (meteorological name: parhelion), also known as a mock sun, or phantom sun, is an atmospheric phenomenon that typically consists of a bright spot to the left and/or right of the sun.
Sun dogs are a member of a large family of atmospheric halos, created by light interacting with ice crystals in the atmosphere.
Photo by: Rick Bohn/USFWS. Posted on Flickr by the US Fish & Wildlife Service, 1/3/17.
https://certainmeasureofperfection.wordpress.com/is-three-sunnes-everards-take-on-the-tregony-parhelic-event-of-dec-1621/