Building a New Milky Way Spectator: The Extremely Large Telescope (ELT) | ESO

Building a New Milky Way Spectator: The Extremely Large Telescope (ELT) | ESO

This picture shows the Milky Way galaxy flowing over the European Southern Observatory’s Extremely Large Telescope (ELT). As the light of the Milky Way band appears to pour into the ELT, the enormous cranes around it seem to do the same while they further advance the telescope. Once the assembly is complete, the soon-to-be largest telescope in the world will be breaking down the light above in unparalleled detail. 

The very bright and orange patch in the Milky Way right above the open dome is the core of our galaxy, with its filamentary dark clouds of gas and dust. The stars in the Milky Way center look redder partly because they are older and partly because dust reddens them, similar to how particles in our atmosphere make the Sun look red at sunrise or sunset.

Focusing back down on Earth, the ELT will scrutinize the pristine night sky above the Chilean Atacama Desert with unprecedented precision. It will help us learn more about the close environment of Sagittarius A*, the supermassive black hole at the center of our galaxy. It will analyze the atmospheres of exoplanets, answer questions about the births and deaths of stars we yet cannot even begin to ask, and explore how galaxies form and evolve, among many other exciting questions. We eagerly await the mysteries of the cosmos the world’s biggest eye on the sky will unveil. 

The Extremely Large Telescope (ELT) is a massive building. It is almost as tall as London's Big Ben clock tower and larger than Rome's Colosseum. The construction materials used for the ELT include: 10,000 tonnes of steel, 30 million bolts or 500 km of cables.

The ELT stands at Cerro Armazones in Chile's Atacama Desert. 
Altitude: 3,046 meters
Planned year of technical first light: 2027

Learn more about ESO’s ELT at: https://elt.eso.org

Image Description: This image shows the open metallic dome of the Extremely Large Telescope (ELT) at the center of the picture taking up the lower half of the frame. At the top, like a river the Milky Way band horizontally pours into the ELT. The construction site of the ELT is surrounded by cranes, while the Milky Way lights up the sky in various colors. One patch of the Milky Way shines the brightest, the center of the galaxy.

Credit: C. Letelier/ESO
Release Date: Aug. 18, 2025

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