Chapter 24, Problem 31Q

To determine

The color of the sky if the earth had no atmosphere.

Answer to Problem 31Q

The color of the sky would be black if the earth had no atmosphere.

Explanation of Solution

Introduction:

When light travels from one medium to another medium, then, part of the light gets absorbed by the particles of the previous medium. This phenomenon is known as scattering of light.

Due to scattering of light, the sky appears blue. Light is scattered in all directions from the sun by the molecules of air present in the atmosphere. So, the scattering of light decreases as $\frac{1}{{\lambda }^4}$

Hence, the blue light is scattered and the sky looks blue. But, if there is no atmosphere that means no air molecules will be present to scatter light from the sun. Hence, the sky would be black and the only light would be seen from the stars or planets and the sun.

Conclusion:

Hence, the color of the sky would be black if the earth had no atmosphere.