Construction has finally begun on the European Extremely Large Telescope (E-ELT), with the first stone laid in a ceremony last week. Being built by the European Southern Observatory (ESO) on the 3,046 m (9,993 ft) high summit of Cerro Armazones in Chile, the E-ELT is set to be the world's largest optical and infrared telescope.

The location was chosen because of its high percentage of cloudless nights and low light pollution, and construction was first given the green light back in 2014. The huge facility is expected to take about a decade to build from then, and the E-ELT is still on track for completion in 2024.

To mark the beginning of construction, which includes the laying of the first stone and the connection of the facility to the Chilean electrical grid, a ceremony was held at the neighboring Paranal Observatory, 20 km (12 miles) east of the E-ELT site. Attendees included the President of the Republic of Chile, Michelle Bachelet Jeria, and Tim de Zeeuw, the Director General of ESO, as well as a host of other Chilean government officials and ESO scientists and engineers.

"With the symbolic start of this construction work, we are building more than a telescope here: it is one of the greatest expressions of scientific and technological capabilities and of the extraordinary potential of international cooperation," President Bachelet says in a statement.

When it's up and running, the E-ELT will be the largest optical and infrared telescope in the world. Its main mirror is 39 m (128 ft) in diameter, dwarfing other telescopes that are vying for the title, including the Giant Magellan Telescope, which contains seven mirrors for a combined 25.4 m (82 ft), and the Thirty Meter Telescope, with a segmented mirror of – you guessed it – 30 m (98 ft).

The structure itself will weigh some 5,000 tonnes, with a moving mass of 3,000 tonnes in a rotating dome 85 m (279 ft) wide. According to the ESO, that makes the facility itself the largest ever built for an optical and infrared telescope.

With that extremely large mirror, the E-ELT will be trained on the heavens to study exoplanets, supermassive black holes, the nature of dark energy and the formation of galaxies in the early universe. The telescope has been designed to correct for atmospheric distortions, meaning the images it captures will be 16 times sharper than those the Hubble Space Telescope is capable of.

"The ELT will produce discoveries that we simply cannot imagine today, and it will surely inspire numerous people around the world to think about science, technology and our place in the Universe," says de Zeeuw.

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