The Atacama Desert (towards the Andes)

The Atacama Desert (towards the Andes)

The Atacama Desert of Chile is the driest place on Earth.  The desert is bounded in the west by the Chilean Coastal Range, which blocks moisture from the Pacific.  On the east of the Atacama run the mighty Andes Mountains which catch almost all the rainfall from the Amazon Basin.  Thus trapped between ranges, the desert receives 4 inches of rain every thousand years.  Because of the dryness, people are very sparse in the Atacama: they are found only at rare oases or as desiccated (but well preserved) mummies lying in pits.

The high altitude, dryness, and lack of nearby cities (with their lights and radio waves) make the Atacama a paradise for astronomers.  On a mountaintop 8000 feet up on the Atacama side of the Andes, engineers and scientists are working to put together one of the wonders of this age.


The Giant Magellan Telescope (hereafter the “GMT”) will be a miracle of engineering.   When it is completed in 2019 it will be larger than any telescope on Earth.  The scope is so giant that it will be mounted in a huge open, moving building (rather than the gun-turret-like buildings observatories are traditionally housed in).  No organization on Earth is capable of making a mirror large enough for the necessary purposes, so seven immense 8.4 meter mirrors are being used together to create a single optical surface with a collecting area of 24.5 meters (80 feet in diameter). The mirrors are the pinnacle of optics: if they were scaled up to the size of the continental United States, the difference between the highest and the lowest point would only be an inch.


The scope will be much more powerful than the Hubble telescope and take much clearer pictures despite being within the atmosphere of Earth.  In the past decade, telescope makers have used cutting edge engineering to compensate for atmospheric distortions.  To do so they fire multiple lasers grouped around the primary mirrors high into the atmosphere.  These beams of light excite sodium atoms in the sky which fluoresce—creating tiny “stars” of known wavelength, which serve as points of reference for the adaptive optics.  The official website of the GMT further explains the mechanism used to counteract atmospheric turbulence once these benchmarks are obtained:

The telescope’s secondary mirrors are actually flexible. Under each secondary mirror surface, there are hundreds of actuators that will constantly adjust the mirrors to counteract atmospheric turbulence. These actuators, controlled by advanced computers, will transform twinkling stars into clear steady points of light. It is in this way that the GMT will offer images that are 10 times sharper than the Hubble Space Telescope.

The telescope is designed to solve some of the fundamental mysteries about the universe. Scientists hope it will help them find out about the nature of dark matter and dark energy (which are thought to make up most of the mass of the universe).   Astronomers also hope to find out how the first galaxies formed and (perhaps) to ascertain the ultimate fate of the universe.  Most excitingly of all, the telescope should be large enough to peek at some of the exoplanets we are discovering by the thousands.  If life exists anywhere near us, the GMT should provide us with compelling evidence in the next twenty years.


The National Science Foundation was initially going to contribute heavily to the telescope but, since the United States Government has become indifferent to science and knowledge, other institutions have been forced to pick up the slack.  The scope is being built by a cooperative effort between The University of Chicago, The University of Texas at Austin, The Australian National University, The Carnegie Institution for Science, Harvard University, The Korea Astronomy and Space Science Institute, the Smithsonian Institution, Texas A&M University, & The University of Arizona (so you can probably help out by donating to any of these institutions, particularly the lovable University of Chicago).