An international team of scientists from the Sloan Digital Sky Survey (SDSS), including Penn State astronomer Donald Schneider, announced that they have completed a map of the locations of 200,000 galaxies.

The SDSS is two separate surveys in one: galaxies are identified in two-dimensional images (right), then have their distance determined from their spectrum to create a two-billion-lightyear deep three-dimensional map (left) where each galaxy is shown as a single point, the color representing the luminosity—this shows only those 66,976 out of 205,443 galaxies in the map that lie near the plane of Earth’s equator.

The new SDSS results are the most accurate measurements to date of how the density of the Universe fluctuates from place to place on scales of millions of lightyears. These and other cosmological measurements agree with the theoretical prediction for a Universe composed of 5% atoms, 25% dark matter and 70% dark energy. The larger the scales that are used to average the data, the more uniform the Universe appears.

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