The Giant Magellan Telescope (GMT) is an extremely large telescope currently under construction. When completed, it will have a primary mirror 24.5 meters in diameter and a total collecting area of 368 square meters. This makes it the largest optical telescope in the world by far, and its light-gathering power will be about 10 times that of the largest existing telescope, the Keck I Telescope in Hawaii. The GMT is being built by a consortium of institutions from around the world, including the Carnegie Institution for Science, Harvard University, MIT, Texas A&M University, and others.
Construction of the GMT began in 2009 at Cerro Las Campanas Observatory in Chile. When completed, it will be able to observe objects with an angular resolution up to 10 times better than that of the Hubble Space Telescope. It will also have a field of view more than 100 times larger than that of Hubble. With these capabilities, astronomers using the GMT will be able to study planets around other stars in detail, map out dark matter distribution in galaxies, and search for signs of life on exoplanets.
The GMT project is led by Patrick McCarthy (Carnegie Institution for Science) and Wendy Freedman (University of Chicago). For more information on the Giant Magellan Telescope project, please see their website: http://www.gmto.org/.