No flies on Rama: The flying bugs illusion

Looping animation on a blue background: a red bug and a black bug fly clockwise along identical circular orbits, always on opposite sides of the circle.

These two bugs fly clockwise along circular orbits of the same size, in all 3 movies. They are in counter phase; one is at 6 o’clock when the other is at 12 o’clock.

The same two bugs, still flying identical clockwise circular orbits, now over a background image of a kneeling Rama and a seated woman that moves clockwise in step with the left bug.

Now the right orbit looks twice as big as the left orbit, because the clockwise moving background is in phase with the left-hand orbit but in counter-phase with the right-hand orbit, which it enhances.

The same two bugs flying in identical orbits, now over a background image of a kneeling Rama and a seated woman that moves counterclockwise.

The orbits look elliptical, wide on the left and tall on the right.The background moves counter-clockwise and is in counter-phase with the horizontal components of the left fly but the vertical components of the right fly.