How can we see cosmic background radiation?

When scientists observed radiation in areas of the sky where it shouldn't have been present, they discovered the cosmic microwave background.

When astronomers mapped out the known universe, they discovered that there were vast voids between all of the visible galaxies. Galaxies, by nature, produce enormous amounts of radiation, which we can easily detect, but when they looked into those dark regions, they still found radiation—not nearly as much as they would have in a galaxy—and reasoned that this radiation was the remnants of the big bang.

In the microwave region of the electromagnetic spectrum, cosmic background radiation can be seen with specialized equipment like radio telescopes.

Cosmic background radiation, also known as cosmic microwave background (CMB) radiation, is a form of electromagnetic radiation that fills the universe and is a remnant from the early stages of the universe. It can be observed using instruments that detect microwave radiation, such as radio telescopes or specialized satellites equipped with microwave detectors. These instruments can detect the faint signals of CMB radiation that permeate the universe, allowing scientists to study its properties and gain insights into the early universe.