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. Some of these journeying photons will slam into other particles and disappear; a minuscule fraction will be captured by telescopes on Earth. But the vast majority of stellar photons continue traversing the cosmos, creating a ubiquitous if faint glow that scientists call extragalactic background light. Here:A superbright galaxy called a blazar sends out a flood of radiation . On its way to Earth, some of that radiation slams into vestiges of light from all the stars that have ever existed. Credit: JPL-Caltech/NASA
Posted on: Sat, 07 Sep 2013 11:15:00 +0000
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