In simple terms, twinkling of stars is caused by the refraction taking place on
passing of light through different layers of a atmosphere
The effects of twinkling are reduced by using a larger receiver aperture . This effect is known as aperture averaging.
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.