A Rare Phenomenon, the Brocken Spectre, Was Spotted on Rainbow Mountain in Peru

At the summit of Rainbow Mountain, at an altitude of over 5,000 meters, a rare atmospheric phenomenon called the Brocken Spectre is often observed. When the sun is low behind a person and dense fog appears in front of them, a huge shadow of the observer appears on the clouds, surrounded by a luminous halo.

The effect is based on optical illusion and diffraction. The shadow appears gigantic because the eye cannot correlate its size with objects on the cloud surface. A glory circle—a colored halo resembling a nimbus—is always visible around the ghost's head. It is formed by the backscattering of sunlight by water droplets.

Due to optical perspective, each person sees the glory circle only around their own head's shadow. On the shifting slopes of Vinicunca, the movement of the fog often creates the illusion of a moving figure, lending a mystical quality to the physical phenomenon.