Visions of the Cosmic Web
The Atacama Desert — the driest, most arid place on Earth — may seem an unlikely place to find a building site. But here, on an isolated mountain far from civilization, something strange is rising from the dusty desert sands. This is the ELT — the Extremely Large Telescope — the most powerful eye on the heavens ever constructed.
The strength of its vision is hard to grasp. For the first time we will be able to directly see planets around other stars, or pick out individual stars in distant galaxies. Astronomers will observe the edge of the Universe, peering back billions of years to watch the birth of the galaxies and the first stars. But somewhat paradoxically, its intense gaze will also reveal the largest structure of the Universe, one that has been almost invisible to us until recently.
For most of history astronomers had no idea of the true scale of creation. Though the night sky might appear crowded, especially if you visit somewhere as remote as the Atacama Desert, most of the stars you can see are only a few thousand light years away. If you are lucky you might spot Andromeda, a faint smudge in the northern sky. If you do — congratulations — you are seeing the most distant object visible to the human eye.
Its distance — two point five million light years — might seem inconceivably far. But then remember that the Universe is at least ninety…