Why Do Stars Twinkle?

Stars twinkle because their light must pass through pockets of Earth's atmosphere that vary in temperature and density, and it's all very turbulent. On rough nights, a star appears to shift position constantly as its light is refracted this way and that.

It's much like watching a coin appear to dance at the bottom of a pool.

Astronomers try to overcome the twinkling by using adaptive optics, in which many small mirrors on the scope adjust constantly to allow for the atmospheric disturbances.

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