DESI Completes Five-Year Survey with Largest 3D Map

The Dark Energy Spectroscopic Instrument (DESI), mounted on a telescope at Kitt Peak National Observatory in Arizona, completed its five-year survey of the sky late Tuesday, producing the largest and most detailed three-dimensional map of the universe ever created. The project, which began collecting data in May 2021, observed light from more than 47 million galaxies and quasars—distant objects powered by supermassive black holes—as well as 20 million nearby stars, far exceeding initial expectations of 34 million galaxies and quasars.

Managed by the U.S. Department of Energy's Lawrence Berkeley National Laboratory and operated on the National Science Foundation's Nicholas U. Mayall 4-meter Telescope, DESI features 5,000 fiber-optic positioners that act like robotic eyes, capturing faint photons from objects billions of light-years away. Every 20 minutes, the instrument repositions to target new sources, building a map spanning 14,000 square degrees of the sky—roughly one-third of the celestial sphere visible from the Northern Hemisphere. This high-resolution view traces galaxy distributions over 11 billion years of cosmic history, providing researchers with unprecedented data...