Cosmic Microwave Background

A second piece of evidence is a cool cloud of microwave radiation that fills the universe. This radiation, a faint remnant of earliest moments of the universe, is called the cosmic microwave background, or CMB, and it exists today. An image of this radiation obtained by the COBE satellite appears throughout this unit and below.

This is how the universe might look from earth orbit if you could see in the microwave portion of the electromagnetic spectrum.