Question

Why do planets not twinkle?​

Answer 1

The light rays which come from them, get refracted many times before they reach our eyes. Due to this, stars seem to be blinking or twinkling. Planets on the other hand, are located near to us, relatively to stars. So the diffraction of light does not occur much and planets do not seem to twinkle.

Answer 2

Planets appear bigger in the sky compared to stars. Because of their larger size, the twinkling effect caused by Earth's atmosphere is less noticeable and doesn't happen as much.