Researchers map 47 million galaxies
- The Dark Energy Spectroscopic Instrument finished its planned five-year survey on April 15, mapping more than 47 million galaxies and quasars in 3D. - DESI used 5,000 fiber-optic robots on Arizona’s Mayall telescope to measure galaxy distances, tracing cosmic structure back roughly 11 billion years. - The map will keep growing through 2028 as researchers test whether dark energy changes over time. (lbl.gov)
Astronomers have finished the biggest high-resolution 3D map of the universe yet, built from more than 47 million galaxies and quasars. (lbl.gov) The project is the Dark Energy Spectroscopic Instrument, or DESI, mounted on the Nicholas U. Mayall 4-meter telescope at Kitt Peak in Arizona. It completed its originally planned five-year survey in April 2026. (lbl.gov) (noirlab.edu) A 3D map of the universe works like a census with distances attached: DESI measures how much each galaxy’s light has been stretched during its trip to Earth. That stretch, called redshift, lets researchers place objects in space and time. (universityofcalifornia.edu) (lbl.gov) DESI gathered those measurements with 5,000 robot-controlled fiber-optic positioners that can lock onto thousands of targets at once. The survey reaches light that began traveling up to about 11 billion years ago. (lbl.gov) (news.ucsc.edu) The main target is dark energy, the name astronomers use for the unknown cause of the universe’s accelerating expansion. By comparing how cosmic structure looks at different eras, DESI can test whether that acceleration has stayed constant. (lbl.gov) (nersc.gov) That question has sharpened over the past year because DESI’s earlier data releases hinted that dark energy may not behave like a fixed cosmological constant. The collaboration said those hints are not yet conclusive, but strong enough to justify extending observations through 2028. (lbl.gov) (news.fnal.gov) The same dataset also includes more than 20 million stars in the Milky Way, which researchers can use to study our own galaxy alongside the distant universe. DESI’s map is not a picture in the usual sense; each point marks a measured object with a calculated distance. (nersc.gov) (noirlab.edu) The exoplanet-AI item circulating alongside this story is a separate astronomy result, not part of the DESI map. NASA said in January that its ExoMiner++ system flagged about 7,000 TESS targets as exoplanet candidates in an initial run. (science.nasa.gov) For now, the headline result is simpler than the physics debate around it: DESI finished the survey it was built to do, and the map is still growing. (lbl.gov)
