Foreground for cosmic infrared background. Infrared image of a starfield, from the constellation of Ursa Major, used as the starting point for viewing the cosmic infrared background radiation. Removing the stars and galaxies from this image leaves only the background infrared radiation, as seen in image R980/229. This background infrared radiation dates from a moment called insFirst Lightins, billions of years ago, around 400 million years after the Big Bang. At this point, the early universe had cooled enough to became transparent to radiation. The continued expansion of the universe stretched (red-shifted) this original light, so now it appears as an background infrared glow. Image obtained by the Spitzer Space Telescope (SST), and published in 2006.