Extremely Large Telescope under construction | Space photo of the day for Dec. 10, 2025
Once completed, this telescope will help usher in a new era of astronomy.
High up in the Chilean Andes, the Extremely Large Telescope (ELT) is set to become the world's largest optical telescope and one of the most ambitious scientific instruments ever built. Developed by the European Southern Observatory, the ELT represents a major leap forward in humanity's ability to study the universe with unprecedented clarity.
What is it?
Construction on the ELT officially began in 2014, with the observatory designed around a segmented primary mirror that's 128 feet (39 meters) wide — nearly five times larger than any current ground-based optical telescope mirror. Once operational, the ELT will use advanced adaptive optics to correct for atmospheric turbulence, yielding images 15 times sharper than those from the Hubble Space Telescope.
Where is it?
This drone image was taken high above Cerro Armazones, the 9,993 -oot-tall (3,046 m) mountain where the ELT is located.
Why is it amazing?
Given its advanced instruments, the ELT's overarching mission is to push observational astronomy into a new precision era. The huge telescope will directly image small, rocky exoplanets and look for possible conditions suitable for life outside our solar system. The ELT will also help scientists study our universe's origins by looking at distant galaxies while also measuring the universe's rate of expansion. This telescope will also be used to study stellar dynamics and how stars are born, evolve and sometimes turn into black holes.
As the ELT's construction nears completion, the world waits to see just what this cutting-edge telescope will show us about the world we live in.
Want to learn more?
You can learn more about the Extremely Large Telescope and other ground-based telescopes.
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Kenna Hughes-Castleberry is the Content Manager at Space.com. Formerly, she was the Science Communicator at JILA, a physics research institute. Kenna is also a freelance science journalist. Her beats include quantum technology, AI, animal intelligence, corvids, and cephalopods.
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