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Activity Discussion Science & Technology Why do stars twinkle?

  • Why do stars twinkle?

    Posted by Adeesha on May 6, 2021 at 5:53 am

    Explain why do the planets not twinkle but the stars twinkle?

    • This discussion was modified 3 years ago by  Adeesha.
    Aruja replied 3 years ago 3 Members · 2 Replies
  • 2 Replies
  • Aruja

    May 8, 2021 at 2:03 pm
    Not Helpful

    The phenomenon behind twinkling of stars is known as ‘atmospheric refraction’.

    When the light from the stars enters the atmosphere of earth, the light from stars undergoes the refraction due to the different density of atmospheric gases (air) on different levels before coming to us. So the refractive index change continuously and refract the light coming from the stars in different amount. In this way, the starlight reaching our eyes increase and decrease due to the uneven density of atmospheric air present in its paths. That’s why they appear to twinkle.

    Planets do not twinkle because they are larger in size and very close to us in compared to stars which are far away from us and large in size. So as we know there are many other planets in our solar system. So planets can be taken as a collection of large number of point sized sources of light. As they are in group, so the starlight that comes from them to our eyes as an individual which basically gives that twinkling effect will be average out of zero, which nullify the twinkling effect of each other.

    • This reply was modified 3 years ago by  Kidpid.

    May 6, 2021 at 6:23 am
    Not Helpful

    The twinkling of stars is a phenomenon observed due to atmospheric refraction.

    The physical conditions of the atmosphere do not remain constant and so, the refractive index of the air continuously changes.

    This leads to continuous change in the direction of the light coming from starsas the changing indexes leads to different extents of bending of light.

    Due to this, the amount of light entering our eye continuously changes leading to our perception that the star sometimes appears brighter and sometimes fainter, I.e., twinkling.

    Now, we can understand the phenomenon with respect to planets.

    Planets are extended sources of light, i.e., they can be thought of as a combination of many point sources of light.

    So, every beam of light coming from each of the comprising point sources experiences different extents of bending.

    But, what happens is that the extent of bending of all the rays combined averages out to zero.

    So, they do not twinkle.

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