Twinkling of stars is mainly due to which phenomena?

Refraction

The correct answer is option 2. Refraction.

The twinkling of stars, also known as stellar scintillation, occurs due to the phenomenon of atmospheric refraction.

When starlight enters the Earth's atmosphere, it encounters layers of air at different temperatures and densities. These variations in density cause the light rays to bend or refract as they pass through the atmosphere. As a result, the apparent position of the star appears to fluctuate slightly, causing it to appear to twinkle.

The amount of twinkling depends on several factors, including the temperature and density fluctuations in the atmosphere, the angle at which the starlight enters the atmosphere, and the distance the light has traveled through the atmosphere.

Twinkling is more pronounced when stars are low on the horizon because their light passes through a thicker layer of the atmosphere, causing more significant refraction. Additionally, turbulence in the atmosphere can also contribute to the twinkling effect by causing rapid changes in air density along the light path.

Overall, the twinkling of stars adds to the beauty of the night sky but can pose challenges for astronomers trying to observe celestial objects with high precision.