Janus discs

Janus discs are a type of optical illusion that consist of two distinct images on opposite sides of a circular disc. When the disc is spun, the images blend together due to the persistence of vision, creating the perception of movement or transformation. Named after the Roman god Janus, who had two faces, these discs illustrate how our brain interprets visual information. They are often used in artistic demonstrations and educational settings to explore concepts of perception, motion, and the interplay between reality and visual cues.