Several hundred galaxies and the huge amounts of gas that permeate them are depicted in this space wallpaper, which shows the core of the Shapley Supercluster, the largest cosmic structure in the local Universe. The supercluster was discovered in the 1930s by American astronomer Harlow Shapley, as a remarkable concentration of galaxies in the Centaurus constellation. Boasting more than 8000 galaxies and with a total mass more than ten million billion times the mass of the Sun, it is the most massive structure within a distance of about a billion light-years from our Milky Way Galaxy. This image was released Oct. 21, 2013.
(Image: © ESA & Planck Collaboration / Rosat/ Digitised Sky Survey )