The heart of a giant telescope photo of the day for Feb. 9, 2026

Atop the mountain Cerro Armazones in Chile, construction is underway on the Extremely Large Telescope (ELT), which will usher in a new era of astronomy when it’s completed. The ELT will be the world’s largest telescope, with a primary mirror that measures 128 feet (39 meters) across.

Astronomy depends as much on location as it does on technology. To observe the faintest and most distant objects in the universe, telescopes need dark, dry and stable skies, conditions that are increasingly rare on Earth. Mountains in the Chilean Atacama Desert, like Cerro Armazones, offer an almost perfect natural laboratory. Situated at high altitude, far from cities, and in one of the driest places on the planet, they provide exceptionally clear nights with minimal atmospheric disturbance.