Free Astronomy Magazine November-December 2026

NOVEMBER-DECEMBER 2026 A group of galaxies nicknamed the Copeland Septet, in the constellation of Leo. Astronomers using images from Kitt Peak National Observatory and Cerro Tololo Inter- American Observatory have created the largest ever map of the sky, comprising over a billion galaxies. The final data release from the am- bitious DESI Legacy Imaging Surveys sets the stage for a ground-breaking 5-year survey with sthe Dark Energy Spectroscopic Instrument (DESI), which aims to provide new insights into the nature of dark energy. [DESI Legacy Imaging Surveys/LBNL/DOE & KPNO/CTIO/NOIRLab/NSF/AURA] sky. The DESI Imaging Legacy Sur- veys are just one step in this venera- ble human tradition,” says Arjun Dey, co-lead of the Legacy Surveys and an astronomer at NSF NOIRLab. “For our team, these data are fun- damental to the investigation of the expansion history of the Universe and the formation of our galaxy. But the skies belong to everyone, and this survey gives everyone the chance to marvel at their wonders.” The DESI Legacy Imaging Surveys were originally conducted to pre- pare for the Dark Energy Spectro- scopic Instrument (DESI) survey. The Legacy Surveys’ 2D map is essen- tially a deep photograph of the sky; it records where galaxies and stars appear and how bright they appear. This crucial step enables DESI to se- lect objects and measure their light in different wavelengths to deter- mine their distances, building the schedule and with vastly more ob- jects than expected. The early re- sults have shown surprising hints that dark energy’s impact may be weakening over time — a paradigm shift that could potentially shape the predicted fate of our Universe. DESI expects to publish improved re- sults using its first five years of data in 2027 and is continuing observa- tions into 2028. Beyond supporting DESI, the Legacy Surveys will be a foundational ref- erence for the next generation of telescopes. As new observatories like NSF–DOE Vera C. Rubin Obser- vatory, jointly funded by the NSF and DOE’s Office of Science (DOE/ SC), and NASA’s Nancy Grace Roman Space Telescope come online, re- searchers can compare their obser- vations with one of the deepest and most comprehensive views of the sky ever assembled. largest high-resolution 3D map ever made. Scientists use this map to study the way galaxies have clus- tered at different ages of the Uni- verse to track dark energy over time. In April 2026, DESI completed its original five-year survey ahead of !