Why Do Stars Twinkle and What Makes Some Shine Brighter Than Others?

Stars twinkle because their light travels through space and then through Earth’s atmosphere on its way to our eyes.

Imagine you're looking at a lamp in a foggy room. The fog makes the lamp look like it's blinking or twinkling, that’s what happens with stars! Earth’s atmosphere is full of moving air, kind of like a wiggly blanket. When starlight passes through this blanket, it bends and shifts a little bit, making the stars seem to flicker.

Some stars are bigger, or they’re hotter, or they're closer to us, just like how a bigger, brighter bulb in your room lights up more than a small nightlight.

If you imagine holding two flashlights, one is tiny and dim, the other is big and bright, the big one will shine more strongly from across the room. That's why some stars appear brighter than others: they're either larger, hotter, or just closer to us!