Have you ever noticed how a coin at the bottom of a swimming pool seems to wobble*? This phenomenon occurs because the water in the pool bends the path of light from the coin.

　　Similarly, stars twinkle because their light has to pass through several miles of the earth’s atmosphere before it reaches the eye of an observer.

　　It is as if we are looking up at the universe from the bottom of a swimming pool. Our atmosphere is very turbulent*, with streams and eddies* forming.

　　These disturbances act like lenses* and prisms* that shift* the incoming light from a star from side to side.

　　In outer space, where there is no atmosphere, stars do not twinkle. This is why the Hubble Space Telescope* can produce the brilliant images of the universe that we have come to know. (SD-Agencies)

　　(Difficulty: senior)