Yesterday officials from the European Southern Observatory announced where they plan to build the E-ELT, short for European Extremely Large Telescope.

If I ever hope to visit it someday, I'd better get in shape.

Summit of Cerro Armazones

Located in Chile's Atacama Desert, the summit of Cerro Armazones is 10,020 feet (3,060 m) above sea level. Click here for a larger view.


The chosen location is the summit of Cerro Armazones, a remote hilltop on the high plateau of central Chile. Topping out at 10,020 feet (3,060 m), it's not nearly the highest perch for a professional observatory. Mauna Kea's summit, for example, is 13,796 feet (4,207 m) above sea level.

But these days telescope location is more about "attitude" than altitude. Key factors include maximizing cloud-free nights, atmospheric stability ("seeing"), very low water-vapor content (for infrared observations), as well as costs of construction and operation. The ESO's site-selection team spent years assessing a short list of five peaks in Chile and on La Palma in the Canary Islands.

Enclosure for ESO's giant telescope

The current design of the European Extremely Large Telescope in its enclosure, which will be nearly 300 feet tall.


With a billion-euro price tag and a construction timetable projecting "first light" by 2018, the world's largest optical telescope will be a monster. Its primary's mosaic of 1,000 hexagonal mirrors will create an aperture 138 feet (42 meters) across. That's a huge engineering leap: four times the diameter of the largest single-aperture optical telescopes today. To put the optics in perspective, the E-ELT's secondary mirror will be bigger than the venerable Hale Telescope's 200-inch primary.

The ESO has prepared a very informative 28-page introduction to the E-ELT — but before you download that, have a look at this nifty series of interactive panoramas.

Now, where'd I put those jogging shoes?


Image of Evan James

Evan James

April 27, 2010 at 6:35 pm

Wow that is great! cant wait until its up and running. looking forward to seeing how it works and what kind of pictures it can take.

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Image of Miroslav Sova

Miroslav Sova

April 27, 2010 at 11:50 pm

Great article! Enjoyed the links to the interactive panoramas and the introduction to e-elt article- make sure to check them out!

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Image of Ronny S

Ronny S

May 6, 2010 at 5:29 am

First, my first thought upon seeing the photograph of the summit was "Gosh... it looks just like a location on Mars!"
Second, how about attaching a link to the mountain's geographical location in some satellite imagery? Such as:,-70.196389&spn=0.1,0.1&t=h&q=-24.5975,-70.196389

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Image of Fred Gnerlich

Fred Gnerlich

May 29, 2010 at 12:09 am

Take it from me, Kelly, you would do better with hiking shoes than jogging shoes to make it up the summit of Cerro Armazones. While on a tour of the Mauna Kea Observatories several years ago, I climbed up to the summit. It wasn't too difficult (maybe I was benefiting from an adrenaline rush) but the steep grade and loose, rocky surface made it a little tricky, especially with jogging shoes. I think better footgear would have helped. Needless to say, it was a real "high" for me standing 13,796 feet above sea level. By the way, it was a lot easier and faster going back down!

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