ESO's Extremely Large Telescope tilted on horizontal axis for first time
The 2,000-tonne structure floated on microscopic oil film in a major engineering milestone.
What to know
- The ELT's 2,000-tonne altitude structure was tilted on its horizontal axis for the first time in October 2026, completing rotation tests on both major axes.
- The massive steel structure floats on a hydrostatic oil film only 120 microns thick—thinner than a human hair—enabling smooth, friction-free movement.
- The milestone demonstrates the engineering precision required for the telescope to point anywhere in the southern sky once fully operational.
European Southern Observatory (ESO) telescope operator and constructorRoberto Tamai ELT Programme Manager
How it unfolded 1 development · click the chart to see its coverage posts
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“The very first movement was just a gentle oscillation of a few centimetres around its balanced position. Watching it, I had the wonderful feeling of gently rocking a baby in its cradle. A rather heavy baby, indeed!”
— Roberto Tamai, ELT Programme Manager -
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2000 tonnes of steel sliding on a few microns of oil! Our Extremely Large Telescope (ELT) was tilted for the first time in October 2026. To point anywhere in the southern sky the telescope needs to rotate on two different axes. A few months ago it on its vertical axis for the first time. Now, tilting on its horizontal axis is another step in the…
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Honestly it's even more impressive to me for the vera c rubin observatory, because not only is that a pretty big telescope in its own right, it has to move really fast for a telescope, swinging multiple degrees and then fully stopping and stabilizing in under five seconds; the thing's built like a tank and anchored directly to virgin bedrock with…
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I simply cannot fathom the concept of tracking a target with milliarcsecond precision while keeping such a massive object from deforming even as it changes direction.
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