Why Do Stars Twinkle but Planets Usually Don’t? | RapidSmartFacts

On clear nights, stars seem to twinkle, but planets usually shine with a

steadier light. What’s the difference? The key is how their light travels through Earth’s

atmosphere. Our air isn’t perfectly still. It’s full of moving pockets of

warm and cool air. Each pocket bends light slightly differently as it passes

through. Stars are so far away that each one is effectively a single

tiny point of light. When shifting air bends that point, the brightness and

position seem to jump around. That shifting creates the twinkle we see.

Planets are much closer and spread out into a tiny disk of light.