Question

    Why do starts twinkle in the

    sky?
    A Distance between starts and earth Correct Answer Incorrect Answer
    B Reflection of light Correct Answer Incorrect Answer
    C Diffractions of light Correct Answer Incorrect Answer
    D Refraction of light Correct Answer Incorrect Answer
    E Starts emit light not continuously but periodically Correct Answer Incorrect Answer

    Solution

    It is an example of optical illusion. They appear to twinkle, because light from the stars has to cross several layers of atmosphere with differing refractive indices to reach earth. As the atmospheric conditions in the different layers keep changing, the starts also appear to fade and shine at different times. Hence, option D is correct. 

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