Cosmic background radiation: the horizon problem

The Universe in Different Frequencies
(*.mov, 7.1 MB)

Wilkinson Microwave Anisotropy Probe mission, map.gsfc.nasa.gov

Astronomy 10 learning goal Q12.4

Illustration of how different forms of electromagnetic radiation are distributed in all directions, and how the cosmic background radiation in the microwave band is nearly isotropic (the "horizon problem"), unless contrast is greatly enhanced.