Astronomers step up search for dark energy.

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The most ambitious project yet to map the three-dimensional structure of the universe in a quest to understand dark energy is underway by astronomers from the University of Arizona, Tucson, and 41 other institutions. "Making a three-dimensional map is essential to understanding why the universe is expanding at an ever-accelerating rate," explains Daniel Eisenstein, UA professor of astronomy and director of the Sloan Digital Sky Survey III, a collaboration of 350 scientists. The project is called the Baryon Oscillation Spectroscopic Survey (BOSS).

The BOSS team is using new, extremely sensitive optical-infrared spectrographs on the Sloan Foundation 2.5-meter telescope at Apache Point Observatory in New Mexico. The goal is to collect spectra for 1,400,000 galaxies and 1,560,000 quasars by 2014. Measuring the spectra, or colors, of galaxies and quasars allows astronomers to determine how far away and how far back in time these celestial objects are.

The...