The Gran Telescopio Canarias in Spain is currently the world’s largest optical telescope with the aperture of its main mirror 10.4 metres across. Despite roughly 8 meters being the maximum size for an accurate single mirror to be built on Earth, such a large size was achieved by joining 36 segments together, but now the Giant Magellan Telescope (GMT) currently under construction at Las Campanas Observatory in Chile is set to claim the title with its huge 25 meter diameter mirror.
The feat will be achieved by stitching seven single-cast mirrors together, one central and six off-axis, which will then have five times the light gathering capability of Gran Telescopio Canarias, and ten times that of the space-based Hubble. Moreover, the $1 billion telescope project scheduled to come online in 2021 will be able to eliminate most atmospheric distortions, and be so powerful that, as Astrophysicist Ethan Siegel explains:
“Distant galaxies will be imaged out to ten billion light years. We’ll be able to measure their rotation curves, look for signatures of mergers, measure galactic outflows, look for star formation regions and ionization signatures. We’ll be able to directly image Earth-like exoplanets, including Proxima b, out to somewhere between 15-30 light years distant. Jupiter-like planets will be visible out to more like 300 light years.”
Equally exciting is the prospect of GMT advancing our understanding of the universe by revealing secrets scientists don’t yet know exist. In the 1920’s, for instance, the 2.54-metre Hooker telescope located at Mount Wilson Observatory lead to Edwin Hubble’s discovery of an expanding Universe; while in the 1990’s/2000’s, NASA’s Hubble Space Telescope captured the Hubble Ultra Deep Field (HDF) and Hubble Ultra-Deep Field (HUDF) that took us to within 400 million years of the Big Bang, and added to our understanding of the number of galaxies that exist. There are therefore great hopes that the Giant Magellan Telescope will lead to seeing the Universe in ways never imagined, and elaborating further, GMT’s director, Pat McCarthy, explained:
“There’s a huge, rich world of unknown things out there to be discovered. It’s things like GMT, its cutting-edge new facilities, that bring out these great discoveries. We hope, once GMT is built, some clever young person comes along and does something completely unexpected with it that changes everything. That would be success.”