The illusion, deemed a legitimate astronomical phenomenon, is created by the sun being shadowed by two smaller twins and making an image of three suns. The effect is known by experts as the 'phantom sun' and unofficially called an 'ice halo'. It generally appears at this time of year when ice crystals create high clouds.
Fortunately, for astronomers and citizens of Changchun alike, the clouds have formed perfectly in order to produce reflected sunlight and the curious 'triple sun'. It also produces an arched rainbow-effect that circles the sun and two surrounding smaller suns. These are both one tenth of the size of the sun itself.