WHO US Department of Energys SLAC National Accelerator Laboratory, US National Science Foundation WHEN 6 months The next time you glance up at the night sky, consider: The particles inside everything you can see make up only about 5% of whats out there in the universe. Dark energy and dark matter constitute the rest, astronomers believebut what exactly is this mysterious stuff? A massive new telescope erected in Chile will explore this question and other cosmic unknowns. Its named for Vera Rubin, an American astronomer who in the 1970s and 1980s observed stars moving faster than expected in the outer reaches of dozens of spiral galaxies. Her calculations made a strong case for the existence of dark mattermass we cant directly observe but that appears to shape everything from the paths of stars to the structure of the universe itself. Explore the full 2025 list of 10 Breakthrough Technologies. Soon, her namesake observatory will carry on that work in much higher definition. The facility, run by the SLAC National Accelerator Laboratory and the US National Science Foundation, will house the largest digital camera ever made for astronomy. And its first mission will be to complete whats called the Legacy Survey of Space and Time. Astronomers will focus its giant lens on the sky over the Southern Hemisphere and snap photo after photo, passing over the same patches of sky repeatedly for a decade. By the end of the survey, this 3.2-gigapixel camera will have catalogued 20 billion galaxies and collected up to 60 petabytes of dataroughly three times the amount currently stored by the US Library of Congress. Compiling all these images together, with help from specialized algorithms and a supercomputer, will give astronomers a time-lapse view of the sky. Seeing how so many galaxies are dispersed and shaped will enable them to study dark matters gravitational effect. They also plan to create the most detailed three-dimensional map of our Milky Way galaxy ever made. If all goes well, the telescope will snap its first science-quality imagesa special moment known as first lightin mid-2025. The public could see the first photo released from Rubin soon after.