My friend Keith and I always wondered why stars twinkle.
Stars look as if they are twinkling because of what happens in the layers of air surrounding the Earth. Dust, water droplets, and pollution gather in these layers. Plus, currents of hot air and cold air bump into each other and move everything around.
As starlight passes through these layers, all the dust and droplets - plus the air movement - make the light bounce around. By the time it reaches our eyes, the light has jiggled so much that it looks twinkly!
It's different for astronauts who are out in space. Starlight doesn't have to pass through the Earth's layers of air to reach the astronauts. So they see bright, steady stars - with no twinkling.