Question

What is atmospheric refraction? Use this phenomenon to explain the following natural events:

Twinkling of stars

Draw diagrams to illustrate your answers.

Explain with the help of a labelled diagram, the cause of twinkling of stars.

Why do stars twinkle?

Why do stars twinkle ? Explain.

Answer 1

Stars emit light on their own; when this light travels through the Earth's atmosphere which has variable optical density, the continuously changing atmosphere refracts the light from the stars in different amounts from one moment to the next. The light seems to be bright and dim as it keeps changing because of continuous refraction through the different layers of the atmosphere of the Earth. Hence, we say light twinkles at night.

 

Answer 2

Stars are considered to be point sources of light as they are far away from the Earth. The light coming from stars, on entering the atmosphere, gets bent because of refraction. Since the atmospheric physical conditions are continually changing, the apparent position of the star also keeps fluctuating. The amount of light entering the eye also varies because different amount of light bends at every instant. This is what gives the stars a twinkling appearance