Uploaded May 2024 | Updated September 2026, 2 weeks ago

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M5, the fifth mirror on the light path of ESO’s Extremely Large Telescope (ELT), has reached an important milestone: its blank, the shaped piece of material that is later polished to become the mirror, has just been finalised.

It might look small compared to the ELT’s enormous 39-metre primary mirror, but in reality, it is the largest tip-tilt mirror in the world. It will move 10 times per second without bending. Together with M4 — a flexible and very fast deformable mirror — they will both correct atmospheric turbulence and telescope vibrations, delivering sharp images.

Learn more about ESO's ELT at: elt.eso.org

Credit:
ESO

Directed by: Angelos Tsaousis
Editing: Angelos Tsaousis
Web and technical support: Gurvan Bazin and Raquel Yumi Shida
Written by: Bárbara Ferreira
Footage and photos: ESO, L. Calçada, A. Tsaousis, M. Wallner.
Music: Jon Kennedy – A Tale of Pizzicato.
Acknowledgement: Mersen-Boostec.

This video can be downloaded on: eso.org/public/videos/ann24008a