World's Largest Telescope Under Construction

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A century ago, scientists believed that the Milky Way represented the full expanse of the cosmos. Thanks to major advances in space tech, we now understand that the Universe extends as far as our telescopes can see—and then much, much farther.

Now, a U.S.-directed international consortium has broken ground on the construction site of the world’s largest earth-bound megascope, which will provide images ten times sharper than those delivered by Hubble. The Giant Magellan Telescope (GMT) will sit atop an arid mountain at the Las Campanas Observatory in Chile’s Atacama Desert, where unobstructed dark skies make for one of the most pristine astronomical viewing locations on the planet.

The GMT’s novel design features an arrangement of seven 27-foot-wide mirrors—the largest single piece astronomical mirrors ever made—into a unique lens. The total light-gathering surface spans 85 feet in diameter, over double the aperture of the world’s current largest telescope. These will work in conjunction with a set of seven smaller, flexible mirrors, which will adjust constantly to adapt to disturbances caused by pockets of varying temperatures in earth’s atmosphere.

Photo courtesy of Giant Magellan Telescope – GMTO Corporation.

The manufacture of each of the GMT’s 20-ton primary mirrors must be completed with painstaking accuracy: Each must be polished within 20 nanometers of perfection. That’s roughly the size of a single grain of glass, or one millionth of an inch. To make matters more complicated, the mirrors are designed on a curve, so that they collect light around a central reflective plate.

“An enormous amount of work has gone into the design phase of the Project and development of the giant mirrors that are the heart of the telescope,” said Patrick McCarthy, President of the GMT Organization, in a press release. “The highest technical risks have been retired, and we are looking forward to bringing the components of the telescope together on the mountain top.”

Slated to be operational by 2021, the GMT will allow astronomers to gaze into the earliest stages of the universe to observe how young stars and galaxies formed, and how stellar matter cast itself into what we now see today. The telescope will offer insights into the nature of dark matter and dark energy, which have remained steeped in mystery due to a lack of adequate observational equipment.

Perhaps most intriguing is the GMT’s potential to make significant contributions in the search for life beyond earth. The resolution of the super telescope’s imaging technology will allow for researchers to assess with greater accuracy than ever before the compositions of exoplanet atmospheres, a step that will be essential in determining which earth-like planets might harbor life.

“The essence of our species is to explore,” McCarthy said. “To find new answers and new meaning for who we are.”

The GMT promises to do just that.

To better understand how the Giant Magellan Telescope’s mirrors will work, watch the video below!