Strong evidence that the Universe is expanding comes from the fact that the light emitted from distant galaxies appears to be ____________.
A) red-shifted
B) blue-shifted
C) green-shifted
D) none of the above

Question

Quizplus · Accepted Answer

The fact that light emitted from distant galaxies appears to be red-shifted (meaning the wavelength of the light appears longer and shifted towards the red end of the spectrum) is strong evidence for the expanding universe, according to the Doppler effect. This means that as galaxies move away from us, the light they emit is stretched and becomes redder due to the expansion of space.

Strong Evidence That the Universe Is Expanding Comes from the Fact