Question

Astronomy

A star’s light is shifted to the blue part of the light spectrum.



What does this mean about the length of light waves and movement of the star?

Please explain your answer.

A.
The wavelengths are getting longer, meaning the star is moving away from the observer.


B.
The wavelengths are getting longer, meaning the star is moving toward the observer.


C.
The wavelengths are getting shorter, meaning the star is moving toward the observer.


D.
The wavelengths are getting shorter, meaning the star is moving away from the observer.

Answer 1

The answer is C because as you go farther down on the the spectrum of electromagnetic waves, the wavelengths get shorter, which means it's moving towards the observer. This is called the Doppler Effect, specifically a Doppler blueshift.