World's Largest Telescope Begins Construction

After nearly a decade of planning, construction of the Giant Magellan Telescope is finally underway. And boy, does it look cool.

Perched high in the mountains of northern Chile, the GMT—whose primary optics consist of 7 separate 8.4-meter (27 foot) diameter mirrors—will proudly claim the title of the largest optical scope ever built. Its mirrors will be capable of focusing more than 6 times the amount of light of the largest optical telescopes today, into images 10 times sharper than those captured by Hubble.


“Every time someone builds a new telescope, we learn something about the universe that we never expected,” Patrick McCarthy, director for the Giant Magellan Telescope Observatory told Gizmodo over the phone. “Astronomy is about discovering new things, and telescopes are our vehicle.”

Working in concert with forthcoming space-based scopes, including the James Webb Space Telescope, the GMT will enable astronomers to peer further back in time than ever before, observing the birth of stars and coalescence of galaxies in the first hundred million years of the universe.

“Hubble has given us great views of how the universe evolved when it was 2 to 5 billion years old,” McCarthy said. “It’s also given us just the most tantalizing view of the earlier universe. Now we’ll be able to look back and see the formation of the very first structures, when the universe went from a uniform sea of gas to stars and galaxies.”


Another key science goal of the GMT will be to get a first good look at some of the exoplanets orbiting nearby stars. This work will pair the GMT with the Transit Exoplanet Survey Satellite, a small, space-based telescope that, like NASA’s Kepler mission, will detect the tiny shadows of distant planets transiting in front of their stars. Unlike Kepler, which focuses on exoplanets 500-1,000 light years away, when TESS flies in 2017, it’ll set its sights on our nearest neighbors, getting the distribution of planets in our cosmic vicinity.


If TESS detects a neighboring world that seems interesting, astronomers will use the GMT to take a closer look, measuring the planet’s mass using the doppler technique. In some cases, GMT might be able to measure the spectral fingerprint of the light filtered through the atmospheres of nearby planets, information which astronomers can use to decode atmospheric chemistry and hunt for signs of life.


A perennial challenge for astronomers is dealing with the distortion of space caused by molecules in our atmosphere. According to McCarthy, the GMT will be outfitted with a brand-new mechanism to help compensate for this. In principle, the technology works a bit like a pair of noise-canceling headphones, except the GMT will be canceling distortions of light rather than sound. After light is filtered through the instrument’s primary mirrors, it hits a smaller set of secondary mirrors, which change shape roughly 2000 times per second to cancel out atmospheric distortion. The result is that when the GMT sets her eyes on the night sky, she’ll see it more clearly than any human, or any piece of ground-based technology ever before.


I, for one, can’t wait to see what we discover.

[Giant Magellan Telescope h/t Mayra Marcotte]

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