The Extremely Large Telescope (ELT) is an astronomical observatory under construction. When completed, it will be the world's largest optical and near-infrared extremely large telescope. Part of the European Southern Observatory (ESO) agency, it is located on top of Cerro Armazones in the Atacama Desert of northern Chile, 23 km from the existing facilities at Paranal Observatory.
The design consists of a reflecting telescope with a 39.3-metre-diameter (130-foot) segmented primary mirror and a 4.25 m (14 ft) diameter secondary mirror. The telescope is equipped with adaptive optics, six laser guide star units, and various large-scale scientific instruments. The observatory's design will gather 100 million times more light than the human eye, equivalent to about 10 times more light than the largest optical telescopes in existence as of 2025, with the ability to correct for atmospheric distortion. It has around 250 times the light-gathering area of the Hubble Space Telescope and, according to the ELT's specifications, will provide images 15 times sharper than those from Hubble.
