A shuriken, our word of the day, is a traditional Japanese concealed weapon that was generally used for throwing, and sometimes stabbing or slashing. They are sharpened hand-held blades made from a variety of everyday items such as nails, knives, washers, and other flat plates of metal. When translated from Japanese, it literally means “sword hidden in the hand”. Here in the west it’s most commonly known as “throwing star”, “ninja star” or inaccurately as “Chinese stars”, though they took many different shapes and designs during the time they were used.
So what does all of this have to do with our latest optical illusion, you ask? Not much except visual similarity, I guess. I just thought it would be cool to mention ninjas and shurikens in the paragraph above. Ok, now let me explain how the illusion works – If you concentrate on the central dot in the animation below, after seeing the first frame consisting of two overlapped colored objects, you get the impression next two frames are showcasing isolated objects filled with appropriate fluorescent color! In reality, all frames except first lack color, and what you perceive as color afterwards is just an afterimage burnt in your retina! Don’t worry though, it only lasts couple of seconds…
