The ground-breaking ceremony for the 39-meter diameter main mirror in the telescope took place Friday on the flattened top of Cerro Armazones, a mountain rising to 3,000 meters in Chile's dry and largely cloudless northern Atacama region.

When fully constructed, the Extra Large Telescope (ELT) conceived by the European Southern Observatory (ESO), a consortium that includes Brazil, Germany, France and Britain, will also have four smaller mirrors.

The main mirror will have 800 hexagonal sections, each with a diameter of 1.4 meters, designed to fit together exactly, and is to be protected by an 80-meter dome (illustrated above).

Jump in observation power

The ESO director general, Dutch astronomer Tim de Zeeuw, said the ELT's main mirror would be five times larger and would gather 13 times more light than most telescopes currently operational.

"The leap between the telescopes we have and the ELT is almost as large as the leap between Galileo's naked eye and his telescope," de Zeeuw said.

Chilean President Michelle Bachelet said the project illustrated the potential for international cooperation.

One of ESO's goals is to search for planets beyond the Solar System where life may be viable, including the recently discovered Trappist-1 and Proxima b systems.

ELT will also enable nighttime clues on dark matter and black holes.

Made in Germany

The largest secondary mirror, spanning 4.2 meters and weighing 3.5 tons, was forged in Mainz, Germany and is reputedly the largest-ever produced convex mirror.

ESO, which has its headquarters near Munich, oversees three other observation locations in Chile's desiccated Atacama region.

The ELT was originally envisaged in the late 1990s and is projected to cost 1.1 billion euros ($1.2 billion), mainly from European donors.

In the United States, competition continues between the Los Angeles-based Caltech university with its Thirty Meter Telescope intended for Hawaii and the Carnegie Science Center's Giant Magellan Telescope, also planned for Chile.

ipj/kl (dpa, AFP)