SSC Geography Sample Paper NCERT Sample Paper-5

  • question_answer
    We observe twinkling of stars due to

    A)  Frequent and periodic fluctuation of temperature of the surface

    B)  Constant change of refractive index of the medium between the stars and the Earth because of temperature variation

    C)  Great distance of stars from the Earth

    D)  Rise and fall of gaseous ball fire inside the stars

    Correct Answer: B

    Solution :

    [b] The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere. Stars (except for the Sun) appear as tiny dots in the sky; as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling).

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