Question

Twinkling of stars is due to
A. Reflection of light
B. Refraction of light
C. Diffraction
D. All

Answer 1

Hint: In order to solve this question, we should have learnt the concept of Atmospheric refraction. Atmospheric refraction is the deviation of light or other electromagnetic waves from a straight line as it passes through the atmosphere due to the variation in air density as a function of height.

Complete step-by-step answer:


The twinkling of stars is due to atmospheric refraction of star-light. The refraction of light caused by the earth's atmosphere having air layers of varying optical density is called atmospheric refraction.


The physical conditions of the atmosphere keep on changing continuously due to which density of air in different layers of atmosphere also keeps on changing.


As a result of this, the refractive index of the various layers of atmosphere also keeps on changing continuously. So, light coming from stars suffers multiple refractions and the amount of starlight reaching the eye also keeps changing and so, due to fluctuation of perceived brightness of the star, they appear like they are twinkling.


Hence, the correct answer is Option B.

Note: Whenever we come up with this type of problem then we should know that stars do not really twinkle; they just appear to twinkle when seen from the surface of Earth. The stars twinkle in the night sky because of the effects of our atmosphere. When starlight enters our atmosphere it is affected by winds in the atmosphere and by areas with different temperatures and densities. This causes the light from the star to twinkle when seen from the ground.