You observe a distant galaxy.You find that a spectral line normally found in the visible part of the spectrum is shifted toward the infrared.What do you conclude?
A)The galaxy is moving away from you.
B)The galaxy is moving toward you.
C)The galaxy has very weak gravity.
D)The galaxy is made purely of hydrogen.
E)The composition of the galaxy is changing.

Question

Quizplus · Accepted Answer

This is an example of redshift, which occurs when the observed wavelength of light is longer than expected due to the Doppler effect. The shift towards longer (infrared) wavelengths implies that the source (galaxy) is moving away from the observer.

You Observe a Distant Galaxy