Slices through the SDSS 3-dimensional map of the distribution of galaxies.
Earth is at the center, and each point represents a galaxy, typically containing about
100 billion stars. Galaxies are colored according to the ages of their stars, with the
redder, more strongly clustered points showing galaxies that are made of older stars. The
outer circle is at a distance of two billion light years. The region between the wedges
was not mapped by the SDSS because dust in our own Galaxy obscures the view of the
distant universe in these directions. Both slices contain all galaxies within -1.25 and 1.25