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What is the reason for the twinkling of stars?
Explosions occurring in stars from time to time
Absorption of light in the earth’s atmosphere
Motion of stars
Changing refractive index of the atmospheric gases
The correct reason for the twinkling of stars is changing refractive index of the atmospheric gases.
Light coming from the stars undergoes refraction on entering the Earth’s atmosphere. This refraction continues until it reaches the Earth’s surface. This happens because of temperature variation of atmospheric air. Hence, the atmospheric air has changing refractive index at various altitudes. In this case, starlight continuously travels from a rarer medium to a denser medium. Hence, it continuously bends towards the normal. The refractive index of air medium gradually increases with a decrease in altitude. The continuous bending of starlight towards the normal results in a slight rise of the apparent position of the star.