Grades K–2 · Earth & Space
Why do stars seem to twinkle?
A star can look as if it is flickering on a clear night. Often the star itself is shining steadily during those quick changes. Its light has a long journey before reaching your eyes.
In the diagramChanging air changes the arriving starlightmoving airchanging view
Near the end of that journey, the light passes through Earth’s air. Moving pockets of air bend the light slightly in changing ways. At one moment more light reaches your eyes, and at another moment less does.
That changing view makes the star seem to twinkle. The air is changing the light’s path. Above most of Earth’s air, the same star would usually look much steadier over those short moments.
About this explanation
Starting knowledge: Recognize a star and understand that its light travels through air before reaching us.
Sources
- NASA StarChild — Why do stars twinkle?