European Mega-Telescope

The money was authorized by the council of the European Southern Observatory (ESO), an ESO press release said.

The so-called Europe Extremely Large Telescope (E-ELT) is budgeted at between 800 million and a billion euros ($1.04-1.3 billion dollars) in total.

A design approved by more than 250 ESO astronomers at a four-day meeting in Marseille, southern France, at the start of the month calls for an optical/infrared telescope with a 42-meter (136.5-feet)-diameter composite mirror, the largest in the world.

The mirror will comprise 906 hexagonal segments, each 1.45 meters (4.7 feet) in size.

Their light will be channeled to an "adaptive optics" system, chiefly comprising a smaller mirror whose shape can be distorted by tiny actuators and helps to correct for image fuzziness that occurs when light passes through Earth's atmosphere.

The design phase should last three years, followed by the start of the building phase.

Telescope ready by 2018

If all goes well, the E-ELT will start operations in 2018, and will be more than 100 times more sensitive than the present-day largest optical telescopes, led by the 10-meter (32.5-feet) Keck telescope in Hawaii.

It could hugely advance knowledge of planets around other stars, the earliest moments of the universe, "super-massive" black holes and enigmatic phenomena called dark energy and dark matter.

"This is really the beginning of a new era for optical and infrared astronomy," said ESO Director General Catherine Cesarsky.

The initial design sketched for the telescope was an OWL ("OverWhelmingly Large") design with a 100-mete (325-feet) mirror, but this was scaled back in 2005 because it was too costly and too complex to build on ESO's budget timescale.

The ESO Council's 11 members are: Belgium, Britain, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Sweden and Switzerland. Spain is expected to join by the end of the year.

ESO already has two large telescopes in Chile, at La Silla and Paranal.