Introduction to Stars, Galaxies, & the Universe
Prof. Richard Pogge
The above image is a map of the large-scale structure of the local universe created using data from the Sloan Digital Sky Survey by Michael Blanton and collaborators. This graph the distribution of 147,986 galaxies in distance for field within 6-degrees of the Celestial Equator. The left and right halves show regions surveyed in the northern and southern galactic hemispheres, respectively. The Earth (in the Local Group) lies at the center of the map. The blank regions above and below are inaccessible because of obscuration by dust in the plane of the Milky Way.
The local universe shows a number of large-scale patterns: sheets and filaments of galaxies surrounding great voids 20-50 Mpc across where the density of galaxies drops a factor of 5-10 (or more). The "Great Wall" is the large structure that stretches across the northern hemisphere in this plot (left-hand wedge, about a quarter of the way out from the center towards the left edge of the diagram).
The image is reproduced from a paper by Blanton et al., 2003, ApJ, 592, 819.