A Map of the Universe

A map of the universe produced by the Sloan Digital Sky Survey contains 200,000 galaxies at distances of up to two billion light years, and spread out across 2400 square degrees of sky. According to Sloan astronomer Michael Blanton (NYU), this is "the best three-dimensional map of the universe to date." The Sloan effort uses a telescope in New Mexico optimized to record spectra from many galaxies at the same time. One of the standout features of the map is the Sloan Great Wall of galaxies, some 1.37 billion light years long and the "largest observed structure in the universe" (preprint:astro-ph 0310/0310571) Combined with data from other telescopes, such as the Wilkinson Microwave Anisotropy Probe (WMAP), the new Sloan observations help tamp down uncertainties in several pivotal astronomical numbers. The new best value for the Hubble constant is 0.70 with an uncertainty of about 0.04; the amount of energy in the universe vested in matter is 30% with an uncertainty of 4%; the upper limit on neutrino mass is 0.6 eV; and the age of the universe is 14.1 billion years with an uncertainty of 1 billion (Preprint astro-ph/0310/0310723; visit Sloan website).