scintillation

In astronomy, scintillation refers to the twinkling of stars. This phenomenon is not caused by the stars themselves but by the Earth's atmosphere. As starlight travels through the atmosphere, turbulence—variations in temperature and density of air flows—causes the light to bend and distort. This bending makes stars appear to twinkle, a visual effect that is more pronounced for distant stars that appear as tiny points of light. Planets, being closer and appearing as small disks, generally do not twinkle because their larger light source cancels out atmospheric distortions. The amount of atmosphere a star's light passes through also affects scintillation, with stars closer to the horizon appearing to twinkle more. This atmospheric turbulence also impacts the sharpness of images seen through telescopes, a concept known as "seeing".123