Rare natural phenomenon "Sun Dog" appearing in the sky over Greece - A second smaller "Sun" appeared to the left of the Sun and a large bright halo ring formed on the horizon at sunset, as the "Sun Dog" phenomenon is in progress. The rare optical illusion lasted for about 30 minutes

Sun dog, (or sundog) or mock sun, formally called a parhelion in meteorology, is an atmospheric optical phenomenon that consists of a bright spot to one or both sides of the Sun.
The sun dog is a member of the family of halos caused by the refraction of sunlight by ice crystals in the atmosphere. They can be seen anywhere in the world during any season, but are not always obvious or bright. Sun dogs are best seen and most conspicuous when the Sun is near the horizon.