Question

With respect to refraction of light explain how we can say that stars appear to twinkle in the sky?

Answer 1

Twinkling of celestial bodies (generally stars) is caused by the scattering of light in the earth’s atmosphere. The stars appear twinkling point sources of light because they are very far from earth. The light from stars passes through the layers of air undergoing multiple refractions, this deviates the light from its path and the point source (star) seems to twinkle. Sometimes, when the atmosphere is very stable the stars don’t seem to twinkle. Sometimes, when the atmosphere is very unstable even planets seem to twinkle!