Question

Which phenomenon exhibited by light is demonstrated in the twinkling of stars ?

• A. Reflection
• B. Dispersion
• C. Scattering
• D. Refraction

Hint:

Planets do not twinkle because they are much closer to Earth and appear as extended sources of light (a collection of many point sources). The twinkling effect from each point averages out, resulting in a steady glow.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The twinkling of stars is an optical phenomenon caused by the Earth's atmosphere. Stars are very far away and act as point sources of light.

Step 2: Detailed Explanation:
The phenomenon responsible is atmospheric refraction.
\[\begin{array}{rl} \bullet & \text{The Earth's atmosphere is composed of layers of air with different temperatures and densities, and thus different refractive indices.} \\ \bullet & \text{As the light from a distant star enters the atmosphere, it continuously bends or refracts as it passes through these constantly changing layers.} \\ \bullet & \text{This continuous refraction causes the apparent position of the star to shift slightly and the amount of light reaching the observer's eye to fluctuate.} \\ \bullet & \text{This fluctuation in the light's intensity and apparent position is perceived as twinkling.} \\ \end{array}\]

Step 3: Final Answer:
The twinkling of stars is caused by the atmospheric refraction of starlight.