(You may need to zoom in, or look close)
Caution: If this illusion makes you feel dizzy or uncomfortable, then look away.
This image is an example of a "peripheral drift" anomalous motion illusion.
Although the image is NOT animated, most people will see the circles rotating, especially as they move their eyes around.
The image is a variation of the famous "Rotating Snakes" illusion, created by Akiyoshi Kitaoka, Professor of Psychology at Ritsumeikan University, Kyoto, Japan.
For further examples, see Akiyoshi's Illusion Pages