Uploaded July 2026 | Updated September 2026, 2 weeks ago
This video shows how, for the first time, the structure of ESO's Extremely Large Telescope (ELT) was rotated around its vertical axis. ESO staff at the construction site, together with Ace/Cimolai’s team, who are leading the construction of the dome and main structure, rotated the telescope first by hand by a few centimetres, and then a full rotation using auxiliary motors. While this may seem small, the entire structure currently weighs around 3500 tonnes, which will further increase up to 4600 tonnes once the mirrors and science instruments are installed. The structure rests on a layer of oil just 80 microns thin that allows the telescope to rotate smoothly. Testing this motion is thus key to ensure that this massive telescope can point at all areas of the southern sky.
Discover more about ESO’s ELT at: elt.eso.org
Watch our ELT playlist here: youtube.com/watch?v=OWCBm8b0IBc&list=PLSZ2Jv0bEZHy7el0mIrOMRKkhCw8pemaZ
Credit:
ESO
Editing: Martin Wallner
Written by: Bárbara Ferreira
Music: Jon Kennedy -- Electronic Sound Pictures
Footage: Apical, Jose Porte/Chepox, Alejandro Ubilla/Chepox
Web and technical support: Raquel Yumi Shida
Acknowledgements: Cimolai
More information and download options: eso.org/public/videos/potw2627a
#astronomy #engineering
This video shows how, for the first time, the structure of ESO's Extremely Large Telescope (ELT) was rotated around its vertical axis. ESO staff at the construction site, together with Ace/Cimolai’s team, who are leading the construction of the dome and main structure, rotated the telescope first by hand by a few centimetres, and then a full rotation using auxiliary motors. While this may seem small, the entire structure currently weighs around 3500 tonnes, which will further increase up to 4600 tonnes once the mirrors and science instruments are installed. The structure rests on a layer of oil just 80 microns thin that allows the telescope to rotate smoothly. Testing this motion is thus key to ensure that this massive telescope can point at all areas of the southern sky.
Discover more about ESO’s ELT at: elt.eso.org
Watch our ELT playlist here: youtube.com/watch?v=OWCBm8b0IBc&list=PLSZ2Jv0bEZHy7el0mIrOMRKkhCw8pemaZ
Credit:
ESO
Editing: Martin Wallner
Written by: Bárbara Ferreira
Music: Jon Kennedy -- Electronic Sound Pictures
Footage: Apical, Jose Porte/Chepox, Alejandro Ubilla/Chepox
Web and technical support: Raquel Yumi Shida
Acknowledgements: Cimolai
More information and download options: eso.org/public/videos/potw2627a
#astronomy #engineering
