Why does the configuration of planets, as collections of numerous point-sized sources of light, result in a cancellation of the twinkling effect?

The twinkling effect, also known as stellar scintillation, occurs when the light from a celestial object, such as a star, passes through the Earth’s atmosphere. The Earth’s atmosphere is not uniform and consists of different layers with varying temperatures, pressures, and densities. These variations in the atmosphere cause the light passing through it to refract and scatter, leading to the twinkling effect.

In the case of planets, which are collections of numerous point-sized sources of light when observed from a distance, the twinkling effect is reduced compared to individual stars. This reduction is due to the fact that the light from different points on the planet’s disk reaches the observer, and the overall effect is an average of the light coming from various parts of the planet.

The combined light from these different points on the planet’s surface tends to average out the fluctuations caused by atmospheric turbulence. While the light from one point on the planet’s surface may be affected by atmospheric conditions, the light from another point may not be experiencing the same conditions at the same time. As a result, the overall effect is a more stable and less twinkling appearance compared to individual stars.

In contrast, stars are essentially point sources of light, and the light from a single point on a star’s surface is more susceptible to atmospheric turbulence, leading to a more noticeable twinkling effect. Planets, with their extended disks of light, provide a smoother and averaged-out appearance, reducing the impact of atmospheric turbulence on the observed light.