Question

how does twinkling of stars occurs?

Answer 1

The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because weare viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere.

Answer 2

Hola Friend ✋✋✋

Twinkling of Stars is occured due to ★ Atmospheric Refraction ★

Our Earth's atmosphere has several layers and in those layers refractive index will be different.

♦ The atmospheric refraction occurs in a medium of gradually changing refractive index. Since the atmosphere bends the star light towards in normal the Apparent position of the star is slightly different from the actual position.
The starlight appear slightly higher than its actual position.

Since the physical condition of Earth's atmosphere are not stationary , like there will be movements in air particles in the atmosphere, the path of rays of light coming from the stars was wearing slightly the apparent position of the star fluctuates and the amount of star light entering eye flickers , in which Peter latest twinkling of stars ★.

Hope it helps