Atacama desert, Cerra Paranal, Chile
Technology reporter Katia Moskwitch writes in BBC science news (link):
The VLT is one of several telescopes in the Atacama Desert, set up by the European Southern Observatory (Eso). Eso is an international research organisation headquartered in Munich, Germany, and sponsored by 15 member countries.
The main component of an optical telescope is a mirror, and the light coming from a particular object being observed with separate telescopes - such as a star, a nebula or a galaxy - first gets reflected off individual mirrors.
And this is where the interferometer comes into play.
It directs the light underground into tunnels, where specific instruments compensate for the delay that inevitably exists when more that one telescope is used.
Once there is no delay, the light is combined into one single beam - and the image astronomers get is what would have been produced by a single telescope with a gigantic mirror and a much better zoom.
"With four telescopes, you can start thinking about triple stars or young stars surrounded by a protoplanetary disk - a disk of dust and gas that forms planets."
"Now, the zoo of objects accessible to us will be much bigger"...said Jean-Philippe Berger, a French astronomer involved in the project.
BBC Science news 5 February 2012