Look at the picture. It is not animated. Repeat, it is not animated. Your eyes are making it groovy. Very groovy.
Still not convinced? Stare at one spot for a few seconds. Everything stops moving and the picture ceases to be groovy. Or, you could gaze at the black center of each circle and the picture will stop grooving (but move your eyes to the next black center and the previous one will move after take your eyes away from it. Way on!