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hello sir

sir i am having doubt that one question confusing me to understand the question is "why and how do stars twinkle and why planets do not twinkle"
sir please help me sir.

thank you

Hello ravimeti,

The light from stars travel across the universe without twinkling. It is as the light enters our atmosphere that the twinkle develops. The reason for the twinkle is that turbulence in the various layers of our atmosphere (and to some extent in the plasma in our solar system) causes the light to be refracted and otherwise battered.

Download this Wikipedia article

and this Irish Astronomical Journal article

The 2nd paragraph of the Wikipedia article discusses the reason for twinkling. It is still a simple discussion, but a bit more detailed than mine. Refer to the Irish Astronomical Journal article. The 3rd and 4th paragraph of this article also discusses the reasons for twinkling.

For the reason that planets do not twinkle, refer again to the Irish Astronomical Journal article. The first full paragraph of the last page makes the statement that in fact smaller planets and satellites do twinkle.  Even though stars are much larger than our planets, stars are considered to be point sources of light because of the distance to the stars. To our eye they are no larger than a point of light. So any variation is noticeable. Planets in the sky are larger than a "point of light" because they are much closer; and the large planets in particular subtend a larger angle between lines from your eye to the left edge and the right edge. A very small angle, but larger than the angle from your eye and a star's left and right edges. So you are not as likely to notice the twinkle of a planet.

I hope this helps,


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Steve Johnson


I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.


I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University

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