Why+do+they+twinkle?

Why do they twinkle? **When the air moves, the dust particles obstruct the star light and stars appear to twinkle but they do not. Stars twinkle because their light has through many kilometres of the earth's atmosphere before it reaches the eye of an observer. It acts like a lens and a prism shifting the light from side to side with very minor movements. The incoming beams bend rapidly sideways.**