There is a simple trick about this optical illusion, but first take a look these two images below and see what they look like to you. Do those balls appear to be on the ground on the first and up on the second image? They sure do if you orientate by the shadow below the balls. We can't mistrust the shadow, or can we? Yes we can. Now look at the shadow position on the first and the second image and you'll see that balls stand on exactly the same place they did on the first image, but the shadow is moved. isn't it?