Planets appear to shine unwaveringly as a result of the distance between the planets. Even with high-resolution telescopes, stars look like mere dots, seeming to twinkle due to refraction when passing through the earth’s atmosphere. Planets, on the other hand, are much closer to the earth which appear as small discs through a telescope.
Planets do not twinkle
Planets are much closer to the earth and are seen as extended sources. So, a planet may be considered a collection of many point-sized light sources. Although light coming from individual point-sized sources flickers but the total amount of light entering our eye from all the individual point-sized sources average out to be constant. Thereby, planets appear equally bright and there is no twinkling of planets.