Remnant glow of ancient stars offers glimpse of universe’s past
On the next clear night, go outside and look up. If you’re away from city lights, you may be amazed by the darkness of the sky between the stars. But what looks like inky black isn’t really so. Even the darkest of night skies still contains the light of all the stars that ever shone.
Photons, or particles of light, are born in the nuclear furnaces of stars and then jet outward through the empty depths of space. Still more photons are ejected when stars explode as supernovas and from superheated matter that swirls in its death throes before being sucked into a black hole.