Flying bluebottle illusion: No flies on Rama Two bluebottles fly around identical circular orbits. They are in counterphase; one is at 12 o'clock when the other is at 6 o'clock. The moving background makes one orbit look twice as large as the other. However, they are still really the same size. When the background moves counterclockwise, in phase with the horizontal component of one orbit, and the vertical component of the other, the two orbits look like a wide and a tall ellipse. However, both are still circular. Back to Stuart Anstis Demo's Page