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What causes the twinkling of stars on a clear night?
AAtmospheric refraction continually shifts the apparent position of stars
BStars themselves vary in brightness under typical conditions
CStars come closer and recede across all cases
DCosmic rays interfere with starlight
Answer & Solution
Correct answer: A. Atmospheric refraction continually shifts the apparent position of stars
1. Air at different altitudes has different temperature and density.
2. Density variations refract starlight slightly differently at each instant.
3. The apparent position of a star wobbles minute by minute.
4. The eye perceives this rapid change in brightness as twinkling.
5. Planets are too large to twinkle because their varied paths average out.
6. So atmospheric refraction causes the twinkling.
_Source: NCERT Class 10 Science Ch 11 'Human Eye and the Colourful World'_
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