Mountaintop levelled for stadium-sized telescope

The European Southern Observatory, or ESO, has blasted the top of a 3,000-metre high mountain, the Cerro Armazones in northern Chile. This will provide the flat surface for the observatory’s new European Extremely Large Telescope that will be housed in a stadium-sized dome on the mountaintop.

The planned €1 billion (US$1.3 billion) facility will have a mirror 39 metres in diameter, making it the largest optical and infrared telescope ever built and enabling ground-breaking discoveries.

The telescope will be large enough to find the twin of Earth around another star – if it exists – see deep enough into the universe to a time when the very first stars were forming and, for the first time, measure changes in how fast our universe is expanding.

Astronomers describe the E-ELT, as the telescope is called, as “truly a next-generation telescope”. Noting that it is larger than all the current eight-metre telescopes combined, they say this represents as big a leap in their ability to see the sky as when Galileo surpassed the human eye with his first telescope.

“This facility is a light-bucket, collecting 100 million times more light than our eyes, and eight million times that of Galileo’s telescope,” one astronomer said. “This means we can learn about the faintest objects in the night sky, be they distant galaxies or nearby but tiny planets.”

The project involved a consortium of 15 nations to support the ambitious advance in efforts to understand the world around us and will revolutionise many fields of astronomy.

“It can find the twin of Earth at the right distance from its star to host life, see back in time to how the very first stars formed in the universe and even measure the change in how space itself is expanding for the first time,” the astronomers say.

“To achieve the precision required you want to build as high above the atmosphere as possible to stop the stars ‘twinkling’ but even at three kilometres altitude we have to correct for this with adaptive optics.

“This means we fire laser beams into the sky and then subtly deform the entire 39-metre mirror to counteract the twinkling until the lasers appear like points again, making for a perfectly clear image as if the telescope was in space.”

* ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory. It also operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor.