Construction began on 26 May 2017 on the European Extremely Large Telescope (ELT), which when completed will be the world’s largest optical telescope. The telescope will be located in Chile’s Atacama Desert.Director General of ESO, Tim de Zeeuw, and President of the Republic of Chile, Michelle Bachelet Jeria marked the attendance in the ceremony to inaugurate the construction of the telescope.The size of the ELT has the potential to transform our understanding of the universe, say its backers, with its main mirror that will measure some 39 meters (43 yards) across.Located on a 3,000 meter-high mountain in the middle of the Atacama desert, it is due to begin operating in 2024. Moreover it will add to and refine astronomers’ burgeoning discoveries of planets orbiting other stars, with the ability to find more smaller planets, image larger ones, and possibly characterize their atmospheres, a key step in understanding if life is present.Apart from this The dry atmosphere of the Atacama provides as near perfect observing conditions as it is possible to find on Earth, with some 70 percent of the world’s astronomical infrastructure slated to be located in the region by the 2020s.The ELT is being funded by the European Southern Observatory, an organization consisting of European and southern hemisphere nations. Construction costs were not available but the ESO has said previously that the ELT would cost around 1 billion euros ($1.12 billion) at 2012 prices.($1 = 0.8949 euros)An edition, Oxford University scientists are playing a key role in the project. They will be responsible for the design and construction of its spectrograph; HARMONI, an instrument designed to simultaneously take 4000 images, each in a slightly different colour.