The temperature of the CMB is hotter on one side of the sky than on the other by approximately 3 milliKelvin.What does this tell us?
A) The true center of the universe is in the direction of the hotter side of the CMB.
B) Earth is moving with respect to the CMB.
C) Earth is near the center of the universe's expansion but not exactly at the middle.
D) The universe is expanding faster on one side of us than on the other.
E) The universe is homogeneous but not isotropic.

Question

Quizplus · Accepted Answer

This temperature difference is due to the Doppler effect, indicating that Earth is moving relative to the CMB, causing a blueshift in the direction of motion and a redshift in the opposite direction.

The Temperature of the CMB Is Hotter on One Side