Astronomers have completed the largest three-dimensional map of the universe to date using data from the Dark Energy Spectroscopic Instrument (DESI) in Arizona. The map, part of the DESI Legacy Imaging Surveys, contains 5.6 trillion pixels and captures around 4 billion celestial objects such as galaxies, stars, black holes and asteroids. It covers 75 percent of the sky, combining visible light and near-infrared wavelengths collected over five years. Obstructions from the Milky Way's dust and stars limited full-sky coverage, so researchers directed DESI's 5,000 robotic sensors above and below the galaxy's plane for clearer deep-space views. The project built on 13 years of prior work and involved more than 160 scientists. Over 1,800 scientific papers have already used the data. David Schlegel of the Lawrence Berkeley National Laboratory, co-lead of the Legacy Surveys, said the imaging viewer has become foundational in astronomy research. A previous DESI release mapped distances of 47 million galaxies and quasars, reconstructing 11 billion years of cosmic expansion linked to dark energy.
The map's scale is impressive, yet it still cannot observe large portions of the sky obscured by our own galaxy. This limitation reveals how even advanced ground-based instruments remain constrained by Earth's position within the Milky Way. The data is now accessible online for public exploration through the Legacy Imaging Viewer.
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