Ultraviolet and visible light emitted by all the stars that ever existed is still coursing through the universe. Astronomers refer to this "fog" of starlight as the extragalactic background light (EBL). Image released Nov. 1, 2012.

Astronomers have spotted light from the very first stars in the universe, which are almost as old as time itself.

Shortly after the Big Bang 13.7 billion years ago, the universe cooled enough to let atoms form, which eventually clumped together to create the first stars. Ever since these stars ignited, their light has been filling the universe, creating a pervasive glow throughout space that each successive generation of stars adds to.

Gamma rays interact with the EBL, which gives astronomers a means to probe the stellar content of the cosmos. Image released Nov. 1.

The new measurements should help astronomers answer some of their most basic questions about the first generations of stars, such as how quickly they formed, and how soon after the birth of the universe the first stars came to be, researchers said.