A slice through largest-ever three-dimensional map of the Universe. Earth is at the left, and distances to galaxies and quasars are labelled by the lookback time to the objects (lookback time means how long the light from an object has been traveling to reach us here on Earth). The locations of quasars (galaxies with supermassive black holes) are shown by the red dots, and nearer galaxies mapped by SDSS are also shown (yellow). The right-hand edge of the map is the limit of the observable Universe, from which we see the Cosmic Microwave Background (CMB) &#8211; the light &#8220;left over&#8221; from the Big Bang. The bulk of the empty space in between the quasars and the edge of the observable universe are from the &#8220;dark ages&#8221;, prior to the formation of most stars, galaxies, or quasars. Click on the image for a larger version.  Image Credit: Anand Raichoor (École polytechnique fédérale de Lausanne, Switzerland) and the SDSS collaboration