Why do stars twinkle in the night sky?

Stars appear to twinkle because their light passes through Earth’s atmosphere, which is full of moving air layers with varying temperatures and densities. These atmospheric variations cause the light to bend, or refract, in different directions as it reaches our eyes. The effect, known as “stellar scintillation,” is more pronounced when stars are closer to the horizon, as their light travels through more of the atmosphere. In contrast, planets twinkle less because their light appears as a larger, steadier source. This phenomenon adds a magical quality to stargazing, even though it’s rooted in atmospheric turbulence.