DESI maps distant objects to study dark energy. The instrument is installed on the Mayall Telescope, shown here beneath star trails captured in a long-exposure image.
Credit: KPNO/NOIRLab/NSF/AURA/B. Tafreshi

For centuries, scientists have sought to understand the vastness of the universe. Now, thanks to the Dark Energy Spectroscopic Instrument (DESI) and the work of scholars like astrophysicist and American University Professor Johannes U. Lange and his undergraduate researcher Abby Fisher (BS physics ’26), the most detailed 3D map of the cosmos is now publicly available.

Created to shed light on dark energy—the elusive force behind the universe’s accelerating expansion—the newly released DESI dataset captures details on 18.7 million galaxies, quasars, and stars. Offering an unparalleled glimpse into the cosmos, it maps the precise distances of millions of galaxies and boasts more than twice as many unique extragalactic objects as all previous 3D spectroscopic surveys combined.

This data will help scientists tackle some of the biggest mysteries in astrophysics, from the evolution of galaxies and black holes to the fundamental nature of dark energy. It is also free and available to everyone—from students to space aficionados—interested in exploring the Universe.

“With just 13 months of data, we already saw the first hints that dark energy may not be a cosmological constant, signaling that we may be at the cusp of a new era of our understanding of the Universe,” says Lange. “Cosmology is a very collaborative research field. By making this world-class data public, we invite researchers around the world to further improve our understanding of the cosmos.” 

Cosmic Breakthroughs and the Universe’s History

Lange and Fisher are part of the international DESI collaboration, which involves more than 900 researchers from more than 70 institutions and is managed by the US Department of Energy’s Lawrence Berkeley National Laboratory. DESI focuses on analyzing the redshift of galaxies—how their light stretches as the universe expands—allowing scientists to map the cosmos in three dimensions.

One aspect of Lange’s work is to analyze DESI's maps of the Universe, together with maps of gravitational lensing, the light deflection of massive objects predicted by Einstein's theory of gravity. This allows us to test dark energy through its impact on the formation of the largest structures in the Universe. Beyond dark energy, “by measuring redshifts, we can also associate every galaxy with a certain time in cosmic history,” he explains. “This allows DESI to track the evolution of stars, black holes, and galaxies through most of the Universe's history.”

For Fisher, who plans on pursuing a PhD in Astrophysics, being a part of DESI has opened many exciting opportunities. “Through DESI collaborations, I stay updated on the latest computational techniques, data analysis tools, and cosmological findings, which are extremely valuable for my academic growth,” she says. 

The Future for a Telescope with 5,000 Robotic Eyes

DESI is mounted on the Nicholas U. Mayall Telescope in Arizona, where it operates like a cosmic time machine. Each night, its 5,000 fiber-optic sensors capture light from distant galaxies, recording their positions in three dimensions. The sensors capture light from the objects, recording their positions in three dimensions.

Over the next five years, DESI is planning on mapping more than 50 million galaxies and quasars, building on its already staggering 270-terabyte dataset—just a fraction of what’s to come.  

Lange and Fisher will contribute to future studies. “The map we just released comes from the first year of a five-year observing program,” says Lange. “The big question on everybody's mind is whether, when all is said and done, will we need to fundamentally revise our model of the Universe?”

Fisher says she appreciates the opportunity to make an important contribution to changing how we think about the universe. “As an undergraduate woman in astrophysics, my identity as a researcher has been reinforced by DESI,” she says. “The support from Dr. Lange and the collaboration have bolstered my confidence and commitment to pursuing a career in science.”

To Learn More

To learn more about DESI’s data release and future updates, it’s all free and available to access through the National Energy Research Scientific Computing Center. Space fans can also explore some of DESI’s data through an interactive portal: the Legacy Survey Sky Browser.