Astronomers create world's largest mirror

Astronomers at the Paranal observatory have created the world's largest mirror by linking up four telescopes to operate as a single device. 


The telescopes together "form a virtual mirror of 130 metres in diameter" (BBC News). The link-up gives scientists a chance to look at the universe in much more detail than previously. 


The BBC reports:
"The process that links separate telescopes together is known as interferometry.

In this mode, the VLT (Very Large Telescope) becomes the biggest ground-based optical telescope on earth.

Besides creating a gigantic virtual mirror, interferometry also greatly improves the telescope's spatial resolution and zooming capabilities.

VLTI, or the VLT Interferometer, has been used since 2002 to link together up to three VLT telescopes, as well as four small auxiliary telescopes that reside beside the big ones on the same platform at Cerra Paranal mountain, at 2,635m altitude.

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."