Twinkling of stars is due to atmospheric

(a) dispersion of light by water droplets

(b) refraction of light by different layers of varying refractive indices

(c) scattering of light by dust particles

(d) internal reflection of light by clouds



  • The different atmospheric layers have varying optical densities (refractive indices). 
  • This results in star-light undergoing refraction multiple times before it reaches our eyes. 
  • So a star appears to change its position (twinkle) to the human eye because of atmospheric refraction. 

Why do stars twinkle-01.jpg

So, the correct answer is (b)

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo