Question

Why do stars twinkle while planets do not ?

Answer 1

Stars are present very far away from the earth. They are visible as point sources. 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.