Question

due to which phenomenon of light the stars twinkle at night in the sky

Answer 1

refraction of light

Answer 2

Due to atmospheric refraction phenomenon of light the stars twinkle at night in the sky.

Atmosphere has different layers of densities.

The light deviated due to the different air densities in the atmosphere depends on altitude as it a function called atmospheric refraction.

When increases the densities of air decreases the velocity of light causes refraction. It becomes high when there is high temperature variations occur in environments.

This is the causes of twinkling of stars.