The European Extremely Large Telescope, also known as the alien hunter, will be the world's largest optical telescope. Its mirror alone will be 137 feet wide, half the size of a regular football field.

The whole structure will weigh 2,800 tonnes, making it the heaviest of all telescopes as well. It will gather 13 times more light than existing earthbound telescopes and can even provide images 16 times sharper than the Hubble Space Telescope's.

European astronomers took years to decide on the final design of the alien hunter telescope.

"At the end of the three-year final design study, we will know exactly how everything is going to be built, including a detailed costing," said Catherine Cesarsky, the European Southern Observatory's director general. "We then hope to start construction and have it ready by 2017, when we can install instruments and use it."

The E-ELT will find its home in Chile, where Foreign Minister Alfredo Moreno signed an accord with the European Southern Observatory. The Chilean government will donate 189 acres of land around the Cerro Armazones mountain. And in return, they will have 10 percent of the observing time on the huge telescope.

Construction will begin in early 2012 and the target year for operation is in 2018. The revolutionary telescope is designed to see the deepest parts of the universe and provide clear images of planets, stars and other galaxies.