What celestial process causes a true star to appear to twinkle when viewed from Earth?

Answer

Disturbance of light rays by Earth’s atmosphere from a distant point source

Stars emit their own light traveling across vast distances; this light is slightly disturbed by Earth’s atmosphere, causing the phenomenon known as twinkling, which occurs because the star acts as a single, distant point source.

What celestial process causes a true star to appear to twinkle when viewed from Earth?
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