The Dark Energy Spectroscopic Instrument (DESI) is mapping millions of celestial objects to better understand dark energy: the mysterious driver of our universe’s accelerating expansion. Today, the DESI collaboration released a new collection of data for anyone in the world to investigate. The dataset is the largest of its kind, with information on 18.7 million objects: roughly 4 million stars, 13.1 million galaxies, and 1.6 million quasars (extremely bright but distant objects powered by supermassive black holes at their cores).

While the experiment’s main mission is illuminating dark energy, DESI’s Data Release 1 (DR1) could yield discoveries in other areas of astrophysics, such as the evolution of galaxies and black holes, the nature of dark matter, and the structure of the Milky Way.

“DR1 already gave the DESI collaboration hints that we might need to rethink our standard model of cosmology,” said Stephen Bailey, a scientist who leads data management for DESI and works at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). “But these world-class datasets are also valuable for the rest of the astronomy community to test a huge wealth of other ideas, and we’re excited to see the breadth of research that will come out.”

DESI is an international experiment that brings together more than 900 researchers from over 70 institutions. The project is led by Berkeley Lab, and the instrument was constructed and is operated with funding from the DOE Office of Science. DESI is mounted on the U.S. National Science Foundation’s Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (a program of NSF NOIRLab) in Arizona.

DESI’s data release is free and available to access through the National Energy Research Scientific Computing Center (NERSC), a facility at Berkeley Lab where DESI processes and stores data. Space fans can also explore some of DESI’s data through an interactive portal: the Legacy Survey Sky Browser. 

The new dataset vastly expands DESI’s Early Data Release (EDR), containing roughly 10 times as much data and covering seven times the area of sky. DR1 includes information from the first year of the “main survey” collected between May 2021 and June 2022, as well as from the preceding five-month “survey validation” where researchers tested the experiment. 

Objects in DESI’s catalog range from nearby stars in our own Milky Way to galaxies billions of light-years away. Because of the time it takes light to travel to Earth, looking out in space is akin to looking back in time. DESI lets us see our universe at different ages, from the present day to 11 billion years ago.

Although DR1 is just a fraction of what DESI will eventually produce, the 270-terabyte dataset represents a staggering amount of information, including precise distances to millions of galaxies. The release contains more than twice as many extragalactic objects (those found outside our galaxy) as have been collected in all previous 3D surveys combined. 

Within its first year of operations, DESI became the single largest spectroscopic redshift survey ever conducted, sometimes capturing data on more than 1 million objects in a single month. For comparison, its predecessor, the Sloan Digital Sky Survey (SDSS), collected light from 9 million unique objects over roughly 25 years of operations. In 2024, DESI researchers used the data in DR1 to create the largest 3D map of our universe to date and make world-leading measurements of dark energy.

“The DESI project has maintained the pace of making 3D maps of the universe that are 10 times larger every decade,” said David Schlegel, one of the lead scientists at Berkeley Lab for both DESI and SDSS. “