Astronomy and spaceflight - Stars and galaxies - Stellar scintillation
Why do stars appear to twinkle in the night sky?
Correct!
Stars actually shine fairly steadily. Their apparent twinkling occurs when their light passes through Earth's atmosphere. Moving layers of air with different temperatures and densities continually alter the light's path slightly. As a result, the star's apparent brightness and position fluctuate. Planets usually twinkle much less because they appear as small disks rather than tiny points of light, so atmospheric distortions average out more strongly.
Source: NASA StarChild
