The cosmic background radiation is
A) the flux of visible radiation in empty space, contributed by all visible stars in the universe.
B) the radio noise generated by Earthbound transmitters, spreading out into space since about 1920.
C) the beam of atomic nuclei known as cosmic rays that continuously rain down on Earth from all directions in space.
D) low-intensity radio noise, with a 3 K blackbody temperature, almost uniform in intensity in all directions.

Question

Quizplus · Accepted Answer

The cosmic background radiation, also known as the cosmic microwave background (CMB), is indeed low-intensity radio noise that exhibits a nearly perfect blackbody spectrum at a temperature of about 2.725 K. It is almost uniform in all directions, providing strong evidence for the Big Bang theory.

The Cosmic Background Radiation Is