Question

The sun is rotating about its own axis. The spectral lines emitted from the two extremities of its equator, for an observer on earth will show

• A. red shift for both the extremities.
• B. blue shift for both the extremities.
• C. red shift for one extremity and blue shift for the other extremity.
• D. no shift

Answer 1

The correct option is C red shift for one extremity and blue shift for the other extremity.


Let $AB$ is the equator of the sun and $O$ is an observer situated on earth. The sun is revolving about an axis, as shown in the diagram.

As the sun revolves, the distance $OA$ will decrease while distance $OB$ will increase, at the given instant.

According to Doppler's effect, the observer will see red shift near end $B$ while blue shift near the end $A$.

Hence, $\left(C\right)$ is the correct answer.