Extremely Large Telescope
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The Extremely Large Telescope is an astronomical observatory under construction. When completed, it will be the world's largest optical and mid-infrared extremely large telescope. Part of the European
Artist's impression of the ELT
ESO Council meets at ESO headquarters in Garching bei München, Germany, 2012.
ELT construction status in April 2026
Cerro Armazones at night (2010)
Thirty Meter Telescope
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The Thirty Meter Telescope is a proposal for an extremely large telescope, intended to be built on Mauna Kea, on the island of Hawai'i.
Extremely Large Telescope
…planned extremely large telescopes include the Giant Magellan Telescope with a mirror diameter of 25 m (82 ft) and area of 368 m2 (3,960 ft2), and the Thirty Meter Telescope with a diameter of 30 m (98 ft), and an area of 655 m2 (7,050 ft2). Both of these are also targeting the 2030s for completion. These two other telescopes…
Artist's rendering
The Thirty Meter Telescope design, late 2007
Cultural practitioner Joshua Lanakila Mangauil, along with Kahoʻokahi Kanuha and Hawaiian sovereignty supporters block the access road to Mauna Kea in October 2014, demonstrating against the building of the Thirty Meter Telescope.
Inverted flag being flown next to Mauna Kea access road as a sign of protest, September 2023. Inverted flags can also be used as a distress signal