The Extremely Large Telescope (ELT) has reached a major construction milestone, according to Space.com. Located in Chile's Atacama Desert, the observatory represents one of the most ambitious astronomical engineering projects underway.
The ELT will feature a primary mirror 39 meters in diameter, making it the largest ground-based optical telescope ever built. This enormous aperture enables the instrument to gather far more light than existing telescopes, allowing astronomers to observe fainter and more distant objects with unprecedented clarity.
Construction began in 2014 at the European Southern Observatory's Paranal site in northern Chile. The project brings together resources and expertise from ESO member states, including Germany, France, Italy, and the United Kingdom, along with international partners. Total costs exceed one billion euros.
The telescope's scale creates engineering challenges unlike any previous observatory. The primary mirror consists of 798 individual hexagonal segments, each 1.4 meters across, working together as a single reflective surface. Advanced adaptive optics systems will correct for atmospheric distortion in real time, allowing the telescope to achieve near-theoretical resolution limits.
Reaching this milestone marks progress toward first light, currently targeted for the early 2030s. Once operational, the ELT will tackle questions across astronomy. Researchers plan to search for potentially habitable exoplanets, study the earliest galaxies formed after the Big Bang, and observe supermassive black holes at galactic centers with detail impossible from current ground-based facilities.
The telescope complements space-based observatories like the James Webb Space Telescope, which launched in 2021. While JWST observes primarily in infrared wavelengths from space, the ELT will focus on optical and near-infrared observations from the ground, offering complementary perspectives on the cosmos.
Competing ELT projects operate globally. The Thirty