Why do stars twinkle?

Stars appear to twinkle because of the Earth’s atmosphere. As starlight travels through the atmosphere, it is refracted or bent by layers of air with varying temperatures and densities. This causes the light to change direction slightly, making stars seem to flicker or twinkle. The effect is more noticeable for stars near the horizon, where their light passes through more of the atmosphere. Planets, on the other hand, generally do not twinkle as much because they appear as larger disks of light, which are less affected by atmospheric turbulence. The phenomenon of twinkling is scientifically called “stellar scintillation.”