Explain why the planets do not twinkle but the stars twinkle.

Explanation

Stars are very far away from the earth and behave as almost a point object. The atmosphere is made of several layers and their refractive indices keep on changing continuously. So the light rays coming from the star keep on changing their paths contimuously. As a consequence, the number of rays (or the light energy) entering in the pupil of the eye goes on changing with time and the stars appear twinkling A planet is comparatively nearer to the earth and subtends a larger angle at the eye. So, it may be considered as a collection of large number of point sized objects. Due to atmospheric refraction, quantity of light coming from any one point sized object changes with time but the total light entering the observer.s eye due to all these point objects remains almost the same. As a result the planet does not twinkle.