When we watch countless stars in the clear night sky at night, we always see the stars flashing, flashing. Most people will be puzzled by this, and even wonder whether the stars in the distant space have changed. "Why do the stars twinkle?" In fact, the "twinkling" star actually has no change in light perception, which may be that the star has been quietly shining. What the hell is going on here?

In fact, the "brightness change" in star perception is caused by the interaction between human eyes and starlight and the earth's atmosphere. ?

As we all know, the temperature, density and pressure of the earth's outer atmosphere will change with the height. The difference between temperature and density will inevitably lead to the constant fluctuation of air flow in the atmosphere. This kind of airflow fluctuation is usually called "wind". When light from a distant star enters the earth's atmosphere, it must pass through the atmosphere that is constantly moving violently. In astronomical terms, this kind of atmospheric movement change is generally called turbulence.

Generally speaking, we always think that the light emitted by stars travels in a straight line. However, after the starlight enters the atmosphere, it will inevitably be refracted or scattered in different directions in the atmosphere. At this time, the light emitted by the star will be bent due to the movement of the atmosphere. When the light is scattered or diffused, the brightness of the star will change, and the starlight will also change, making the star image we see with the naked eye "flicker".

So the so-called star flicker is actually the influence of the atmosphere on light, which changes the starlight we receive with our naked eyes. You know, the stars themselves are not flickering, and the stars in outer space will shine out in a balanced and stable way. If you are outside the earth's atmosphere, you will find that the stars observed by the naked eye do not "blink" without atmospheric disturbance. Only when starlight enters the earth's atmosphere, light will bend and spread, which will change the starlight received by human eyes. In the same way, if the turbulence in the atmospheric region is relatively large on a certain day, or the temperature and density are quite different, then the stars will "flicker" more seriously than on a calm night.

On the earth, the stars seem to wink at us, because the earth's atmosphere contains changes in wind, temperature difference and density. Of course, the stars don't blink at people, but humans can "blink" at the stars.

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