Cosmic microwave background

Cosmic microwave background (CMB) is a type of energy that comes from all directions in space. Every single point in the universe has CMB energy, like a very faint and distant light. This energy has been travelling everywhere since the very beginning of the universe, about 13.8 billion years ago. Scientists measure this energy as microwaves, like the microwaves used to cook food, but at much lower levels. The CMB is like a snapshot of the universe in its early stages, when stars and galaxies began to form.