Why do stars twinkle?

Explanation

Stars twinkle due to atmospheric refraction of starlight. As the stars are very far away, they behave as almost point sources of light. On account of atmospheric refractions the path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of star Iight entering the eye flicker.So, sometimes, the star appears brighter and at some other time, fainter. Thus, the stars twinkle