What is primarily responsible for the twinkling of stars?

The twinkling of stars, scientifically known as stellar scintillation, is primarily caused by turbulent air in Earth's atmosphere. As starlight travels through the atmosphere, it encounters various layers of air that have different temperatures and densities. These variations result in the refraction of the light, causing it to change direction slightly as it reaches our eyes. The turbulence can cause the light from the stars to appear to flicker or twinkle.

While atmospheric pressure plays a role in the overall behavior of the atmosphere, it is the turbulence within that pressure system—such as wind currents and thermal fluctuations—that directly leads to the visible twinkling effect. Light pollution and distance from Earth do not cause the twinkling phenomenon; instead, they can affect our ability to see stars clearly, but they do not influence how the light from those stars behaves as it travels through the atmosphere.