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Coming Soon: A Telescope Large Enough to Spot Alien Life

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Lisa Winter

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724 Coming Soon: A Telescope Large Enough to Spot Alien Life

Big changes are coming to Cerro Armazones, a remote mountain in Chile. Construction is about to begin for an area that will house the largest telescope ever constructed on Earth: the European Extremely Large Telescope (E-ELT). Yes, the name is sort of hilarious, but its not lying either. The E-ELT is going to be ten times larger than any other surface telescope and sensitive enough to be able to spot life outside of our solar system.

In order to prep the site for the construction of the telescope, about 80 feet (24 meters) of dirt and rock is going to be blasted off the top in order to create a large plateau. The telescope itself will be, wait for it, extremely large. The main mirror will be 39 meters in diameter, which is far too large to be installed in one piece. It will use nearly 800 mirror segments that are each 1.4 meters in diameter. Each piece will have to be installed with incredible precision, as even microscopic variations can alter the images. Using mirror segments will also allow them to be mass produced, which keeps the telescope’s budget low.


The location was selected because the peak of Cerro Armazones has incredibly dry air. With a drastically reduced amount of water droplets in the air, the images gathered by the telescope will not be as obscured. Telescopes that are used closer to sea level essentially have to peer through a mist, which is unacceptable with the level of clarity required for the E-ELT. The average relative humidity at this site is 15%. As a comparison, the average relative humidity in Phoenix (which causes people who don’t live here to say “it’s a dry heat”) is about 36%. 

About 20 kilometers (12 miles) away, the Paranal complex houses about 100 scientists and staff who operate the four Very Large Telescopes, which have had considerable success in tracking stars at the center of our galaxy. The E-ELT will outperform all of them put together. Because of its size, it will be able to collect light about 10x faster than existing telescope, resolving certain issues that existing telescopes have not been sensitive enough to do.

It is expected that astronomers will begin to use the E-ELT early in the next decade. It will first target Earth-like exoplanets in their host star’s habitable zone in search of the first glimpses of alien life, which would be one of the biggest achievements in observational astronomy ever. The telescope will also observe some of the oldest stars and galaxies in the universe in order to study dark matter and dark energy. Given that the telescope is years away from being functional and there are great strides being made with existing technology, the E-ELT will also be used to probe questions that aren’t even close to being asked yet.


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