Astronomers have unveiled the largest 2D map of the universe, spanning 75% of the sky with 5.6 trillion pixels and cataloging 4 billion cosmic objects, including galaxies, stars, and quasars, through the DESI Legacy Imaging Surveys.
The DESI Legacy Imaging Surveys team has created the most comprehensive 2D map of the universe, combining 263,407 telescope exposures over 13 years to capture 5.6 trillion pixels of data. This map, released in August 2026, covers nearly 4 billion celestial objects, including Messier 96, a spiral galaxy 35 million light-years away, and serves as the foundation for the largest 3D cosmic map yet. It's part of the fabric of astronomy research now,
said David Schlegel, co-lead of the Legacy Surveys and a scientist at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, emphasizing the map’s role in modern astrophysical analysis.
A 13-Year Effort to Chart the Cosmos
The map, developed by the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, was built using data from three ground-based sky surveys: the Dark Energy Camera Legacy Survey (DECaLS), the Mayall z-band Legacy Survey (MzLS), and the Beijing-Arizona Sky Survey (BASS). These efforts combined observations from the U.S. National Science Foundation (NSF) Mayall telescope, the NSF Blanco telescope, and the University of Arizona’s Steward Observatory. Over 160 scientists contributed to data collection, with a team of 20 finalizing the dataset. When you're working with astronomical objects today, you often start by pulling up the Legacy Imaging Viewer to see what you're looking at,
Schlegel added, highlighting the tool’s integration into daily research workflows.
The project’s origins trace back to preparing for DESI’s 3D mapping of the universe, which uses spectroscopic data to measure redshifts and calculate distances. By April 2026, DESI had mapped over 47 million galaxies and quasars, surpassing its initial goals. The 2D map’s high-resolution data enables scientists to study galaxy evolution, detect rare phenomena like gravitational lenses, and investigate dark matter and dark energy. For our team, these data are fundamental to the investigation of the expansion history of the universe and the formation of our galaxy,
said Arjun Dey, co-lead of the Legacy Surveys and an astronomer at NSF NOIRLab.
Beyond DESI: A Resource for All Astronomers
While the map was initially designed to support DESI, its applications extend far beyond. Previous versions of the dataset have already been cited in over 1,800 scientific papers, and the latest release aims to aid in training artificial intelligence systems for future observatories. The data is publicly accessible via the Legacy Survey Sky Viewer and the Astro Data Lab at the Community Science and Data Center (CSDC), allowing researchers and citizen scientists to explore the cosmos. The skies belong to everyone, and this survey gives everyone the chance to marvel at their wonders,
Dey said, underscoring the project’s commitment to open science.
The map’s coverage of 75% of the sky in visible and near-infrared light provides an unobstructed view of the extragalactic universe, free from the dust and stars of the Milky Way. It includes objects like supernovae, black holes, and asteroids, offering a “deep view” of cosmic structures. The project’s legacy is already evident: more than 160 scientists contributed to its creation, and its data will likely remain the most comprehensive 2D map for years to come.
A Legacy for Future Exploration
The DESI Legacy Imaging Surveys mark a milestone in astronomy, blending decades of observational data with modern computational tools. As DESI’s 3D mapping efforts continue, the 2D map serves as both a foundational resource and a testament to collaborative science. With its vast dataset, the project not only advances understanding of dark energy and cosmic expansion but also empowers a new generation of researchers. Explorations of our universe always start with images of the night sky,
Dey said. The DESI Imaging Legacy Surveys are just one step in this venerable human tradition.
The map’s release coincides with broader advancements in cosmic mapping, such as the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), which uses Lyman-alpha emission to study ancient structures. However, the DESI project’s scale and accessibility set it apart, offering a tool that will shape astrophysical research for decades. As Schlegel noted, When you're working with astronomical objects today, you often start by pulling up the Legacy Imaging Viewer
—a practice now embedded in the fabric of modern astronomy.
