DESI Completes Largest, Sharpest 3D Map of the Universe — Over 47 Million Galaxies Catalogued

A global team using the Dark Energy Spectroscopic Instrument (DESI) has produced the largest high-resolution three-dimensional map of the observable universe, cataloguing more than 47 million galaxies and other massive cosmic objects. The dataset is the most detailed cosmic map to date and could play a key role in probing the mysterious force known as dark energy, which drives the universe's accelerating expansion.

DESI is an international collaboration led by the U.S. Department of Energy's Lawrence Berkeley National Laboratory. The instrument, mounted on a telescope in Arizona, surveyed vast swaths of the sky over a five-year campaign to collect the spectra and distances needed to build a precise 3D map. According to NOIRLab, the catalogue contains about six times as many galaxies and cosmic objects as all previous surveys combined.

What DESI Found So Far

Early results from the first three years of DESI data hinted that dark energy's influence on cosmic expansion might change over time, a possibility that would challenge the simple picture of dark energy as a constant energy density pervading empty space (the so-called cosmological constant). While that hint is intriguing, researchers caution that fuller analysis of the complete five-year dataset is required before drawing firm conclusions.

'Ultimately, we are doing this for all humanity, to better understand our Universe and its eventual fate,' said Stéphanie Juneau, an associate astronomer at NOIRLab and member of the DESI collaboration.

'After finding hints that dark energy might deviate from a [cosmological] constant, potentially altering that fate, this moment feels like sitting on the edge of my seat as we analyze the new map to see whether those hints will be confirmed. I’m also very intrigued by the many other discoveries that await in this new dataset,' she added.

Why the Map Matters

Mapping tens of millions of galaxies with precise distance measurements allows scientists to trace the large-scale structure of the cosmos and measure how that structure has evolved over time. Those measurements provide one of the most powerful ways to constrain the properties of dark energy and to test competing cosmological models.

Visualizations of the map place Earth at the center point for reference, with each dot representing a galaxy or massive object. The completed five-year survey gives researchers a vastly richer dataset to analyze and cross-check against other cosmological observations.

Next Steps

The DESI collaboration expects to produce more definitive constraints on dark energy by 2027 as teams finish processing and analyzing the full dataset. Although the initial five-year survey is complete, observations will continue through 2028 to expand the map by roughly 20 percent, focusing on sky regions that are harder to observe and on searching for fainter, more distant objects.

'DESI's five-year survey has been spectacularly successful,' said Michael Levi, DESI director and a scientist at Berkeley Lab. 'We're going to celebrate completion of the original survey and then get started on the work of churning through the data, because we're all curious about what new surprises are waiting for us.'

Bottom line: The new DESI map is a major milestone for observational cosmology. It increases statistical power for dark energy studies and opens opportunities for many other discoveries about galaxy evolution, structure formation, and the distant universe.