Sun Dog or mock sun captured in this stunning video by melkiy582 while riding the train in Moscow.
Image © wikimedia
Sundogs may appear as a colored patch of light to the left or right of the sun, 22° distant and at the same distance above the horizon as the sun, and in ice halos. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sundogs are best seen and are most conspicuous when the sun is low.