Free Astronomy Magazine January-February 2025

48 JANUARY-FEBRUARY 2025 ASTRO PUBLISHING the past 11 billion years, providing the most precise test to date of how gravity behaves at very large scales. DESI is a state-of-the-art instrument that can capture light from 5000 galaxies simultaneously. It was con- structed, and is operated, with funding from the DOE Office of Science. DESI is mounted on the U.S. National Science Foundation Nicholas U. Mayall 4-meter Tele- scope at Kitt Peak National Obser- vatory, a Program of NSF NOIRLab. The program is now in its fourth of five years surveying the sky and is set to observe roughly 40 million galaxies and quasars by the time the project ends. The DESI project is an international collaboration of more than 900 re- Best test yet of how gravity behaves at cosmic scales by NOIRLab Josie Fenske G ravity has shaped our cos- mos. Its attractive influence turned tiny variations in the amount of matter present in the early Universe into the sprawling strands of galaxies we see today. A new study using the first year of data from the Dark Energy Spectro- scopic Instrument (DESI) has traced how this cosmic structure grew over