Imagine walking alone in a desolate area on a mountain path in a dense fog. You see something moving out of the corner of your eye … something big, dark and somewhat sinister. It looks almost like a giant … and it is walking towards you. You have enough control of your faculties to take out your cell phone and record the apparition … because you know no one back home is going to believe your tale. As you stare at the thing, it begins to glow as if walking in an aura or a halo. You hope that if it gets you, someone will find your phone and warn the world of this mountain monster. Miraculously, the shadowing giant disappears and you make safely back down to your car. You rush home to show your scary video to your friends. That is when the mysterious bubble is burst as one of them tell you, “Oh, that’s just a Brocken Spectre. Everybody sees them.” Why didn’t someone warn you? Even worse, why didn’t they tell you that you were just encountering a famous optical illusion made by the fog, the mountain and your own shadow?