Researchers at the Berkeley Lab have released the biggest 2D map of the Universe, covering roughly 75% of the sky in visible and near-infrared light. Built from 263,407 telescope exposures across multiple ground-based and space missions, the dataset provides a deep view of the extragalactic universe unhindered by Milky Way dust, setting the stage for advanced cosmic mapping.
Synthesizing Millions of Exposures into a Single Dataset
Assembling a project of this scale required the integration of massive astronomical datasets. According to project disclosures, the final dataset was produced by a dedicated team of 20 researchers, building upon data collection efforts involving more than 160 scientists.
The map draws on 263,407 telescope exposures harvested from three primary ground-based sky surveys:
- The Dark Energy Camera Legacy Survey (DECaLS) at the NSF Cerro Tololo Inter-American Observatory.
- The Mayall z-band Legacy Survey (MzLS) at the NSF Kitt Peak National Observatory.
- The Beijing-Arizona Sky Survey (BASS) at the University of Arizona’s Steward Observatory.
To fill in observational gaps, the infrastructure was heavily supplemented by multi-year data streams from NASA’s Wide-field Infrared Survey Explorer (WISE) satellite mission alongside other public repositories. The resulting archive captures the precise positions and apparent brightness of stars and distant galaxies across the extragalactic sky.
Laying the Groundwork for the DESI 3D Universe
This massive 2D imaging campaign was not designed as an isolated archive. Instead, it served a vital operational purpose: preparing the foundation for the Dark Energy Spectroscopic Instrument (DESI) survey.
“For our team, these data are fundamental to our 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, highlighting the core motivation behind the massive observational push. “But the skies belong to everyone, and this survey gives everyone the chance to explore the sky and marvel at its wonders.”
Because the Legacy Surveys’ 2D map records the exact celestial coordinates and photometric profiles of these objects, it acts as a targeting catalog. DESI relies on this precise foundational photography to select objects and measure their light across distinct wavelengths. By determining precise distances to these targets, scientists can construct the largest high-resolution 3D map ever made.
Tracking Cosmic Expansion and Dark Energy
Astrophysicists utilize these detailed spatial records to study how galaxies have clustered at varying epochs of cosmic history, providing an empirical method to track dark energy over time.
The timing of this 2D data release coincides with major operational milestones in modern cosmology. In April 2026, the DESI collaboration officially completed its original five-year survey well ahead of schedule, capturing a vastly higher volume of objects than initial projections anticipated. Early findings from this high-density observational campaign have introduced provocative hints that the expansive impact of dark energy might actually be weakening as the universe ages—a potential paradigm shift that could fundamentally alter models predicting the ultimate fate of the cosmos.
With the 2D map now fully accessible to the scientific community and the public alike, researchers are pushing toward the next analytical horizon. The DESI collaboration anticipates publishing refined, comprehensive results drawing from its complete five-year dataset in 2027, while active telescope observations continue onward into 2028.
