Massive 3D Universe Map Charts 47 Million Galaxies Across Cosmic Time

by Aaron Leong — Thursday, April 16, 2026, 10:30 AM EDT

DESI (Dark Energy Spectroscopic Instrument) has, in just five years, completed the largest and most comprehensive 3D map of the universe ever constructed, cataloging over 47 million galaxies and quasars plus 20 million nearby stars. This massive dataset, captured by an array of 5,000 robotic fiber-optic positioners atop the Mayall Telescope in Arizona, also provides scientists with a deeper look at the nature of dark energy and how it might drive the expansion of the universe.

Because light takes billions of years to reach Earth from distant galaxies, the high-res survey gives astronomers a deep-time perspective that can be useful for measuring baryon acoustic oscillations (BAO), which are faint ripples in the distribution of matter that originated in the first moments after the Big Bang. By measuring how the size of these ripples has changed over time, scientists can calculate the expansion rate of the universe at different epochs.

map part — *A thin slice of the map produced by DESI's five-year survey shows galaxies and quasars above and below the plane of the Milky Way. (Credit: Claire Lamman/DESI)*

The new data confirms that the universe’s expansion is accelerating, a phenomenon attributed to the mysterious dark energy, which makes up nearly 70% of everything in existence. However, the DESI results hint that dark energy might not be a constant force, as Albert Einstein once proposed, but rather, the density of dark energy may fluctuate over time, a discovery that could force a revision of the Standard Model of Cosmology.

mayall telescope trail1 — *Star trails over the Mayall Telescope that houses DESI. (Credit: Luke Tyas/Berkeley Lab)*

Constructing this map is the result of incredible feat of engineering. The 5,000 robotic eyes on the Mayall Telescope had to be positioned with a precision of 10 microns (less than the width of a human hair) to capture the photons from millions of light-years away. Every 20 minutes, the telescope reconfigures itself to target a new patch of the sky, basically filming the history of the universe one frame at a time.

While the mission has completed its initial planned survey, the team has already tasked DESI with the next phase of observations. The plan is for the telescope to map through 2028 and expand the current dataset by 20%, from 14,000 square degrees to 17,000 square degrees (the full sky covers 41,000 square degrees). Part of the new coverage will include areas closer to the proximity of the Milky Way, where brighter stars tend to obscure distant object beyond them.