It all started with a big bang.

The top of a 3,000m-high mountain in Chile has been blown off, in order to create a plateau to house the world’s largest telescope.

More than half a million tonnes of rock were removed to create a level surface on which to build the European Extremely Large Telescope (E-ELT). The E-ELT will allow astronomers to look to the observable limits of the universe. It could also provide a detailed view of planets outside our solar system, and show whether any of these planets offer suitable conditions for life.

The E-ELT will have a circular mirror at its centre. The mirror’s 39m diameter is equivalent to almost half the length of a football pitch. Because it is not possible to build such a large mirror in one piece, it will be composed of 798 hexagonal segments, each roughly 5cm thick.

Size matters in astronomy: the E-ELT will gather 8 million times more light than Galileo’s telescope and 26 times more than a single Very Large Telescope.

Aprajita Verma, deputy project scientist for the E-ELT’s British team, said: “The telescope is a really huge step in terms of its scale – it’s so much bigger than anything else. It will give us a deeper and finer view of the universe.”

The telescope will generate images that are 16 times sharper than those from the Hubble Space Telescope, orbiting around Earth. It will also allow astronomers to perform “stellar archaeology”, measuring the properties of the first stars and galaxies, and probing the nature of black holes, dark matter and dark energy.

The Chilean site, in the middle of the Atacama desert, was chosen because its arid climate is perfect for space observation. The sky is almost cloudless, and there is very little water vapour to impede the view into space.

The newly flattened peak of Cerro Armazones is roughly 20km away from Cerro Paranal, home of a Very Large Telescope.

Construction of the E-ELT is expected to take around 10 years. When finished, it will be roughly the height of Big Ben in London. Two more ELTs are also expected to be in operation by the early 2020s.

The E-ELT project, funded by the 15 member states of the European Southern Observatory, will cost more than a billion euros.

Questions for debate and discussion

  1. What is the purpose of a telescope?
  2. Telescopes are very expensive to build. What  are some reasons why countries and organisations keep building them?
  3. Why do you think the telescope will be built on a mountain?
  4. Can you think of any arguments against blasting the top off a mountain and putting a giant telescope there?

Related resources

Stars and the Moon
Help your pupils make a simple telescope to study the stars and find out how to identify their constellations with this great lesson plan and activity.

Exploring space
Find out about space exploration and satellites with this set of collaborative classroom activities.

Teachers TV: A look inside a telescope
A rocket scientist takes you on a journey inside a giant South African telescope.

Tour of the Solar System
Take your class on a tour of the Solar System with this PowerPoint presentation.