The DESI Legacy Imaging Surveys team has released the largest-ever two-dimensional color map of the universe, a 5.6-trillion-pixel dataset containing nearly 4 billion stars and galaxies. The map covers roughly 75% of the sky in visible and near-infrared light, offering a deep view of the extragalactic universe beyond the dust and stars of the Milky Way.
The dataset was built by combining 263,407 telescope exposures collected over 2,285 nights from three ground-based surveys: the Dark Energy Camera Legacy Survey in Chile, the Mayall z-band Legacy Survey in Arizona, and the Beijing-Arizona Sky Survey. These were supplemented by years of data from NASA's Wide-field Infrared Survey Explorer satellite and additional public archives.
More than 160 scientists contributed to data collection, while a core team of 20 produced the final dataset. Processing the hundreds of thousands of images, each with unique atmospheric and telescope conditions, required about a year of code development and eight weeks of computation on the Perlmutter supercomputer at the National Energy Research Scientific Computing Center.
The map is publicly accessible through the Legacy Survey Sky Viewer, allowing astronomers and citizen scientists to explore the sky, search for rare phenomena such as gravitational lenses, and track transient events like supernovae. Over 1,800 scientific papers have already referenced earlier versions of the Legacy Surveys data.
The Legacy Surveys were originally conducted to select targets for the Dark Energy Spectroscopic Instrument (DESI), which uses the 2D map to measure galaxy distances and build a 3D map of the universe. DESI completed its five-year survey in April 2026 ahead of schedule, with early results suggesting dark energy's influence may be weakening over time.
The new map has been used to select DESI targets since June 2026 and will guide the instrument's continued operations through 2028. Researchers expect the dataset to remain the most comprehensive 2D map of the universe for years to come.
Beyond DESI, the map will serve as a foundational reference for upcoming observatories, including the NSF-DOE Vera C. Rubin Observatory and NASA's Nancy Grace Roman Space Telescope. The data will also help train artificial intelligence tools to analyze petabytes of astronomical data and will be used in an astrophysics pilot project within the American Science Cloud.
David Schlegel, co-lead of the Legacy Surveys at Lawrence Berkeley National Laboratory, described the dataset as "part of the fabric of astronomy research now." Arjun Dey, co-lead at NSF NOIRLab, emphasized that the survey gives everyone the chance to explore the sky and marvel at its wonders.
DESI releases biggest 2D map of the universe
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