The Extremely Large Telescope's Fourth Mirror Levitates | ESO

The Extremely Large Telescope's Fourth Mirror Levitates | ESO

With its 39-meter (128-foot) primary mirror, the European Southern Observatory's Extremely Large Telescope (ELT) in Chile will deliver incredibly sharp images of the Universe. However, this requires correcting the blur caused by atmospheric turbulence. Enter the M4, the fourth mirror in the ELT's optical path. This extremely thin levitating mirror will deform up to 1,000 times per second, counteracting turbulence in real time and yielding crisp images of astronomical objects.

The dome of this soon-to-be telescope, planned to be fully completed in 2027, protects the telescope and its sensitive components from the extreme desert environment, and from the Sun during daytime. At night, its two massive sliding doors will open to allow the telescope to observe the night sky, while still protecting it from the wind.

Inside the dome, the construction of the main structure of what will be the world's largest optical and near-infrared telescope is very advanced. With the first light planned for the end of the decade, the ELT and its groundbreaking 39-meter main mirror will tackle major challenges in astronomy and, ultimately, help us understand our place in the Universe.

Learn more about the ELT: https://elt.eso.org

Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, extending along a narrow strip of land between the Andes Mountains and the Pacific Ocean.

Credit: ESO
Directing & Editing: Angelos Tsaousis
Written by: Bárbara Ferreira
Footage and photos: ESO, A. Tsaousis, L. Calçada, M.Wallner, V. Gonzalez, ACe Consortium, AdOptica.
Acknowledgements: AdOptica (Microgate, ADS International)
Duration: 1 minute
Date: June 26, 2026

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