Why stars Twinkle & Planets Don't

Stars appear to twinkle because of the Earth's atmosphere. When starlight enters our atmosphere, it encounters different layers of air with varying temperatures and densities. This causes the light to refract or bend in different directions, leading to the twinkling effect we see from the ground.

In contrast, planets don't twinkle as much because they are not point sources of light like stars. Planets have apparent disks, which means they appear larger in the sky, and this larger apparent size helps average out the effects of atmospheric turbulence. The light from planets also doesn't undergo the same rapid changes in direction as starlight, reducing the twinkling effect.

So, while both stars and planets are distant celestial objects, the difference in their apparent size and the nature of their light sources contribute to why stars twinkle and planets don't twinkle as much.