Question

why do stars twinkle? (4-5m)​

Answer 1

The twinkling of a star is due to atmospheric refraction of starlight. The starlight, on entering the earth’s atmosphere, undergoes refraction continuously due to different layers of atmosphere before it reaches the earth. The atmospheric refraction occurs in a medium of gradually changing refractive index.

also

Stars twinkle because they are so far from Earth that they appear as point sources of light easily disturbed by Earth's atmospheric turbulence, which acts like lenses and prisms diverting the light's path. Large astronomical objects closer to Earth, like the Moon and other planets, encompass many points in space and can be resolved as objects with observable diameters. With multiple observed points of light traversing the atmosphere, their light's deviations average out and the viewer perceives less variation in light coming from them.

Answer 2

We know that the stars emits their own light called starlight due to this they shine on the sky . In other words twinkling is not caused by the stars which are super constant in their brightness it is caused by the earth's atmosphere, as the light  from a star travels towards the earth through the atmosphere it passes through many layers of air varying temperatures and densities . Each of the boundaries of those layers of air refracts the light bending in a slightly direction from moment to moment. So the starlight zigs and zags passes from the star to the telescope on the ground .From our perspective this makes the star appears to be twinkle .

hope it helps you