What is the phenomenon responsible for the twinkling of stars observed from Earth's surface?
Answer and explanation
Correct answer: B. Atmospheric refraction of starlight through air layers of fluctuating optical densities
- Step 1: Starlight travels through successive layers of Earth's atmosphere before reaching an observer's eye.
- Step 2: Because atmospheric temperature and air densities continuously fluctuate, the optical density and refractive index vary dynamically. The continuous bending of light shifts the apparent position and intensity of the point-sized star, producing the twinkling effect.
Answer
Atmospheric refraction of starlight through air layers of fluctuating optical densities.
Why not the others: 'Total internal reflection' explains mirages; 'Dispersion by raindrops' forms rainbows; 'Scattering by dust' explains why the sky is blue.
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