Twinkling of stars is caused by:
AVariation in star brightness
BReflection from clouds at night
CAtmospheric refraction in changing air layers
DPolarisation by upper atmosphere
Answer & Solution
Correct answer: C. Atmospheric refraction in changing air layers
1. Stars are so far away they act as POINT sources.
2. Their light is refracted as it passes through atmospheric layers of varying density.
3. Continuous changes in refraction make the apparent position and brightness fluctuate — twinkling.
4. Planets DON'T twinkle: they are extended sources, fluctuations average out.
_Source: NCERT Class 10 Science Ch 10 §10.4 Atmospheric Refraction_
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