Stars do not really twinkle, they just appear to twinkle when seen from Earth, because of our atmosphere. When light from the faraway stars enters the Earth’s atmosphere, its path is affected by air movement, temperature and the density of various layers in the atmosphere. This causes the light from the stars to refract multiple times before reaching us, making the stars look as if they were blinking.
Planets shine more steadily because … they’re closer to Earth and so appear not as pinpoints, but as tiny disks in our sky. You can see planets as disks if you looked through a telescope, while stars remain pinpoints. The light from these little disks is also refracted by Earth’s atmosphere, as it travels toward our eyes. But – while the light from one edge of a planet’s disk might be forced to “zig” one way – light from the opposite edge of the disk might be “zagging” in an opposite way. The zigs and zags of light from a planetary disk cancel each other out, and that’s why planets appear to shine steadily.
Picture Credit : Google
