List of largest optical reflecting telescopes - wikipedia List of largest optical reflecting telescopes The world 's largest optical reflecting telescopes with an aperture diameter of larger than 8 meters ( hover with mouse over image ). Legend : GTC Keck Subaru HET LBT VLT SALT Gemini ( N ) Gemini ( S ) This list of the largest optical reflecting telescopes with objective diameters of 3.0 metres ( 120 in ) or greater is sorted by aperture, which is one limit on the light - gathering power and resolution of a reflecting telescope 's optical assembly. The mirrors themselves can be larger than the aperture, and telescopes may use aperture synthesis achieved by interferometry. Telescopes designed to be used as optical astronomical interferometers such as the Keck I and II used together as the Keck Interferometer ( up to 85 m ) can reach very high resolutions, although at a narrower range of observations. When the two mirrors are on one mount, the combined mirror spacing of the Large Binocular Telescope ( 22.8 m ) allows fuller use of the aperture synthesis. Largest does not always equate to being the best telescopes, and overall light gathering power of the optical system can be a poor measure of a telescope 's performance. Space - based telescopes, such as the Hubble Space Telescope, take advantage of being above the Earth 's atmosphere to reach higher resolution and greater light gathering through longer exposure time. Location in the northern or southern hemisphere of the Earth can also limit what part of the sky can be observed. Contents 1 Table of reflecting telescopes 2 Top telescopes of 2010 3 Top telescopes of 2000 4 Chronologically 5 Future telescopes 5.1 Under construction or planned construction 5.2 Proposed 6 See also 7 References 8 Further reading 9 External links Table of reflecting telescopes This list is ordered by optical aperture, which has historically been a useful gauge of limiting resolution, optical area, physical size, and cost. Multiple mirror telescopes that are on the same mount, may have a working beam combiner, and can form an image may be ranked by an equivalent aperture to this reported by sources. HET - style or fixed telescopes are ranked by an equivalent aperture also. Reflecting telescopes Name Image Effective aperture m Aper. in Mirror type Nationality / Sponsors Site Built Gran Telescopio Canarias ( GTC ) 7001104000000000000 ♠ 10.4 m 409 '' Segmented, 36 Spain ( 90 % ), Mexico, USA Roque de los Muchachos Obs., Canary Islands, Spain 2006 / 9 Hobby - Eberly Telescope ( HET ) 11 m × 9.8 m mirror 7001100000000000000 ♠ 10 m 394 '' Segmented, 91 USA, Germany McDonald Observatory, Texas, USA 1997 Keck 1 7001100000000000000 ♠ 10 m 394 '' Segmented, 36 USA Mauna Kea Observatories, Hawaii, USA Keck 2 7001100000000000000 ♠ 10 m 394 '' Segmented, 36 USA Mauna Kea Observatories, Hawaii, USA Southern African Large Telescope ( SALT ) 11 m × 9.8 m mirror 7000920000000099999 ♠ 9.2 m 362 '' Segmented, 91 South Africa, USA, UK, Germany, Poland, New Zealand South African Astronomical Obs., Northern Cape, South Africa 2005 Large Binocular Telescope ( LBT ) Phased - array optics for combined 11.9 m 7000840000000000000 ♠ 8.4 m × 2 330 '' × 2 Multiple mirror, 2 USA, Italy, Germany Mount Graham International Observatory, Arizona, USA Subaru ( JNLT ) 7000820009999999999 ♠ 8.2 m 323 '' Single Japan Mauna Kea Observatories, Hawaii, USA 1999 VLT UT1 -- Antu 7000820009999999999 ♠ 8.2 m 323 '' Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 1998 VLT UT2 -- Kueyen 7000820009999999999 ♠ 8.2 m 323 '' Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 1999 VLT UT3 -- Melipal 7000820009999999999 ♠ 8.2 m 323 '' Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2000 VLT UT4 -- Yepun 7000820009999999999 ♠ 8.2 m 323 '' Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2001 Gemini North ( Gillett ) 7000810000000000000 ♠ 8.1 m 318 '' Single USA, UK, Canada, Chile, Australia, Argentina, Brazil Mauna Kea Observatories, Hawaii, USA 1999 Gemini South 7000810000000000000 ♠ 8.1 m 318 '' Single USA, UK, Canada, Chile, Australia, Argentina, Brazil Cerro Pachón ( CTIO ), Coquimbo Region, Chile 2001 MMT ( 1 x 6.5 m ) 7000650000000000000 ♠ 6.5 m 256 '' Single USA F.L. Whipple Obs., Arizona, USA 2000 Magellan 1 ( Walter Baade ) 7000650000000000000 ♠ 6.5 m 256 '' Honeycomb USA Las Campanas Obs., Coquimbo Region, Chile 2000 Magellan 2 ( Landon Clay ) 7000650000000000000 ♠ 6.5 m 256 '' Honeycomb USA Las Campanas Obs., Coquimbo Region, Chile 2002 BTA - 6 7000600000000000000 ♠ 6 m 238 '' Single USSR / Russia Special Astrophysical Obs., Karachay -- Cherkessia, Russia Large Zenith Telescope ( LZT ) 7000600000000000000 ♠ 6 m 236 '' Liquid Canada, France, United States Maple Ridge, British Columbia, Canada 2003 Hale Telescope ( 200 inch ) 7000508000000000000 ♠ 5.08 m 200 '' Single USA Palomar Observatory, California, USA 1948 LAMOST 7000490000000000000 ♠ ( 6.67 m × 6.05 m + 5.72 m × 4.40 m corrector ; effective aperture 3.6 -- 4.9 m ) 4.9 m -- 3.6 m 193 '' Segmented ( 37 + 24 ) PRC ( China ) Beijing Astronomical Obs., Xinglong, China 2008 MMT ( original optics : 6 × 1.8 m ) → see above record for current 6.5 m mirror 7000470000000000000 ♠ 4.7 m ( 6 × 1.8 m ) 186 '' Segmented, 6 USA F.L. Whipple Obs., Arizona, USA 1979 -- 1998 Discovery Channel Telescope 7000430000000000000 ♠ 4.3 m 169 '' Single USA Lowell Observatory, Happy Jack, Arizona, USA 2012 William Herschel Telescope 7000420000000000000 ♠ 4.2 m 165 '' Single UK, Netherlands, Spain Roque de los Muchachos Obs., Canary Islands, Spain SOAR 7000410009999999999 ♠ 4.1 m 161 '' Single USA, Brazil Cerro Pachón ( CTIO ), Coquimbo Region, Chile 2002 VISTA 7000410009999999999 ♠ 4.1 m 161 '' Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2009 Victor M. Blanco Telescope 7000400000000000000 ♠ 4 m 157 '' Single USA Cerro Tololo Inter-American Obs., Coquimbo Region, Chile 1976 Nicholas U. Mayall 4 m 7000400000000000000 ♠ 4 m 158 '' Single USA Kitt Peak National Obs., Arizona, USA 1973 Anglo - Australian Telescope ( AAT ) 7000389000000000000 ♠ 3.89 m 154 '' Single Australia, UK Australian Astronomical Obs., New South Wales, Australia 3.67 m AEOS Telescope ( AEOS ) 7000367000000000000 ♠ 3.67 m 145 '' Single USA Air Force Maui Optical Station, Hawaii, USA 3.6 m Devasthal Optical Telescope ( DOT ) 7000360000000000000 ♠ 3.60 m 141 '' Single India ARIES Devasthal Observatory, Nainital, India 2016 Telescopio Nazionale Galileo ( TNG ) 7000358000000000000 ♠ 3.58 m 138 '' Single Italy Roque de los Muchachos Obs., Canary Islands, Spain 1997 New Technology Telescope ( NTT ) 7000358000000000000 ♠ 3.58 m 142 '' Single ESO countries La Silla Observatory, Coquimbo Region, Chile Canada - France - Hawaii Telescope ( CFHT ) 7000358000000000000 ♠ 3.58 m 141 '' Single Canada, France, USA Mauna Kea Observatories, Hawaii, USA 1979 ESO 3.6 m Telescope 7000357000000000000 ♠ 3.57 m 140 '' Single ESO countries La Silla Observatory, Coquimbo Region, Chile 1977 MPI - CAHA 7000350000000000000 ♠ 3.5 m 3.5 m 138 '' Single West Germany, Spain Calar Alto Obs., Almería, Spain 1984 USAF Starfire 3.5 m 7000350000000000000 ♠ 3.5 m 138 '' Single USA Starfire Optical Range, New Mexico, USA 1994 WIYN Telescope 7000350000000000000 ♠ 3.5 m 138 '' Single USA Kitt Peak National Obs., Arizona, USA 1994 Space Surveillance Telescope 7000350000000000000 ♠ 3.5 m 138 '' Single USA White Sands Missile Range, New Mexico, USA 2011 Astrophysical Research Consortium ( ARC ) 7000348000000000000 ♠ 3.48 m 137 '' Single USA Apache Point Obs., New Mexico, USA 1994 Shane Telescope 7000305000000000000 ♠ 3.05 m 120 '' Single USA Lick Observatory, California, USA 1959 NASA Infrared Telescope Facility 3.0 m 120 '' Single USA Mauna Kea Observatory, Hawaii, USA 1979 NASA - LMT → retired, private 7000300000000000000 ♠ 3 m 118 '' Liquid USA NASA Orbital Debris Obs., New Mexico, USA 1995 -- 2002 See List of large optical reflecting telescopes for continuation of list There are only a few sites capable of polishing the mirrors for these telescopes. SAGEM in France polished the four VLT mirrors, the two Gemini mirrors, and the 36 segments for GTC. The Steward Observatory Mirror Lab cast and polished the two LBT mirrors, the two Magellan mirrors and the MMT replacement mirror. It is currently making the LSST primary mirror and the mirrors for the Giant Magellan Telescope. The Keck segments were made by Schott AG. The SALT and LAMOST segments were cast and polished by LZOS. The mirror for Subaru was cast by Corning and polished at Contraves Brashear Systems in Pennsylvania. This table does not include all the largest mirrors manufactured. The Steward Observatory Mirror Lab produced the 6.5 - metre f / 1.25 collimator used in the Large Optical Test and Integration Site of Lockheed Martin, used for vacuum optical testing of other telescopes. Segmented mirrors are also referred to as mosaic mirrors. Single mirrors are also referred to monolithic mirrors, and can be sub-categorized in types, such as solid or honeycomb. Comparison of nominal sizes of apertures of some notable optical telescopes For the largest reflecting telescopes on the planet, the horizontal indicates the year built and the vertical direction indicates the size of the mirror measured in meters. Countries which contain several of these telescopes are color - coded for identification. Top telescopes of 2010 The largest telescopes are multi-telescope interferometers, and may have longer baselines. However, these astronomical interferometers are less flexible in use, and many interferometers can not form images or see faint objects despite their high peak angular resolution. The largest telescope during the first decade of the 21st century could be either the Gran Telescopio Canarias ( one 10.4 m diameter mirror ), the Large Binocular Telescope ( two 8.4 m diameter mirrors on a binocular mount ), or the Very Large Telescope ( with four 8.2 m telescopes and four 1.8 m auxiliary telescopes ). However, as these were still coming online in the period, the two 10 m Keck Telescopes ( with 85 m aperture synthesis ) were possibly the largest in full scientific operation. Note other wavelengths of telescopes can be much larger physically, such as the 305 m aperture Arecibo radio telescope, but since radio wavelengths are also larger, this does not necessarily translate into brighter or higher resolution images. Reflecting telescopes ( 2010 ) Name Out In Aperture ( m ) Equiv. Area ( m ) Area ( m ) Mirrors Note Altitude ( m ) Gran Telescopio Canarias ( GTC ) 10.4 10.4 74 36 × 1.9 m hexagonal segments for M1 Commissioned 2009 ; Largest single mirror 2267 Southern African Large Telescope ( SALT ) 11 ( max. ) 9.2 66 -- 45 92 × 1 m hexagon ; 11 × 9.8 m mirror HET twin but larger optically. Spherical M1 w / fixed mirror ; spectroscopy ( see here ( 2 ) ) 1783 Keck 1 & 2 10 m each 10 76 ( each ) 36 × 1.8 m hexagons M1 mirrors each largest twin telescopes 152 m total optical area 4145 VLT 1, 2, 3 & 4 8.2 ( each ) 8.2 53 ( each ) 1 x 8.2 m M1 each Largest quadruplet telescope 210 ( total optical area ) 2635 Large Binocular Telescope ( LBT ) 8.4 m each 11.7 111 ( both sides ) 2 x 8.4 m M1 mirrors ; 1 mount Largest Binocular ; largest non-segmented mirrors ; 22.8 m aperture planned 3221 Largest telescopes with interferometer mode, and two image - forming interferometer arrays. Reflecting telescopes ( with interferometer mode ) Name Longest baseline ( m ) Mirrors Area ( m ) Equiv. Note VLTI 200 4 × 8.2 m ( VLT 1, 2, 3, & 4 ) 210 16 Behind schedule in 2010, 4 units at 130 m success in 2012 Keck Interferometer 85 2 × 10 m ( Keck 1 & 2 ) 152 Operations ceased in 2012. Large Binocular Telescope ( LBTI ) 22.8 * 2 × 8.4 m 110 11.9 One telescope mount * ; Fizeau & Amplitude Interferometry CHARA array 330 6 × 1 m 2.45 NPOI 437 6 siderostats ( visible ) Sparse Aperture Optically resolved Mizar ( star ) * Baseline does not reduce with viewing angle Top telescopes of 2000 Reflecting telescopes ( 2000 ) Name Out In Aperture ( m ) Area ( m ) Mirrors Note Altitude ( m ) Keck 1 & 2 10 ( each ) 76 ( each ) 36 × 1.8 m hexagons M1 mirrors each largest twin telescopes, largest aperture mirrors, 152 m total optical area 4145 Hobby - Eberly Telescope ( HET ) 9.2 ( max. ) 66 -- 45 92 x 1 m hexagon ; 11 × 9.8 m mirror Spherical M1 w / fixed mirror ; spectroscopy 2030 Subaru Telescope 8.2 53 1 × 8.3 m M1 Largest single piece mirror ( tied with the 4 VLT ) 4145 UT1 -- Antu 8.2 53 1 x 8.2 m M1 Part of a quadruplet telescope setup 2635 UT2 -- Kueyen 8.2 53 1 x 8.2 m M1 Part of a quadruplet telescope setup 2635 UT3 -- Melipal 8.2 53 1 x 8.2 m M1 Part of a quadruplet telescope setup 2635 Under construction Reflecting telescopes ( 2000 ) Name Out In Aperture ( m ) Area ( m ) Mirrors Note Altitude ( m ) VLT 1, 2, 3 8.2 ( each ) 53 ( each ) 1 x 8.2 m M1 By the year 2000 three unit telescopes were online ; each were the largest single piece mirrors at that time ( tied with Subaru ) 2635 Chronologically Reflecting telescopes ( chronologically ) Years Largest Name Out In Aperture ( m ) Area ( m ) M1 Mirror Note Altitude ( m ) 2009 -- Present Gran Telescopio Canarias 10.4 74 36 × 1.9 m hexagons M1 mirror Segmented mirror 2267 1993 -- 2009 Keck 1 10 76 36 × 1.8 m hexagons M1 mirror Segmented mirror, M1 f / 1.75 4145 1976 -- 1993 BTA - 6 6 26 605 cm f / 4 M1 mirror Mirror replaced twice 2070 1948 -- 1976 Hale ( 200 inch ) 5.1 -- 508 cm f / 3.3 M1 mirror Art deco dome 1713 1917 -- 1948 Hooker ( 100 inch ) 2.54 -- Also used for 1st optical interferometer 1742 For earlier top telescopes see List of largest optical telescopes historically Future telescopes Sketch of the Messier 51 by William Parsons in 1845, later known as the Whirlpool Galaxy Whirlpool Galaxy ( M51A / B or NGC 5194 / 5 ) by NASA / ESA from Hubble Space Telescope in 2005 Below are selected telescopes that are still in the conceptual / proposed stage or still under construction. Under construction or planned construction European Extremely Large Telescope 39.3 m ( first light planned for 2024 ) Thirty Meter Telescope 30 m ( construction halted since April 2015 due to a permit dispute ; first light was planned for 2022 when construction halted ) Giant Magellan Telescope 7 × 8.4 m mirrors giving a 24.5 m aperture with 21.4 m light gathering area ( first light planned in 2021 and completion in 2025 ) Large Synoptic Survey Telescope 8.4 m ( first light planned in 2019 and full operations beginning in 2022 ) James Webb Space Telescope 6.5 m ( May 2020 launch planned ) Pan-STARRS 4 × 1.8 m ( 1 of 4 complete ) Magdalena Ridge Observatory Telescope Array 10 × 1.4 m Daniel K. Inouye Solar Telescope 4 m ( construction started in 2013 ) International Liquid Mirror Telescope 4 m ( dome construction in Devasthal, India, started in 2013 ) San Pedro Martir Telescope 6.5 m ( completion expected for Summer 2018 ) Proposed Advanced Technology Large - Aperture Space Telescope ( ATLAST ), 8 -- 15 m space telescope Chinese Giant Solar Telescope ( CGST ). China aims to build a very large infrared and optical solar telescope, with the spatial resolution expected to be equivalent to an 8 - meter - diameter telescope and light - gathering power equivalent to a 5 m diameter full aperture telescope High - Definition Space Telescope - proposed segmented mirror telescope 39 feet ( 12 meters ) in aperture, placed at the L2 lagrange point Colossus Telescope - proposed 70 - 80 meter diameter telescope for examining exoplanets ( 2010s ) See also Astronomy portal Extremely large telescope List of largest optical refracting telescopes List of optical telescopes List of astronomical interferometers at visible and infrared wavelengths List of largest optical telescopes historically List of largest optical telescopes in the 20th century List of largest optical telescopes in the 19th century List of largest optical telescopes in the 18th century Strehl ratio References Jump up ^ `` Upgraded Hobby - Eberly Telescope Sees First Light McDonald Observatory ''. mcdonaldobservatory.org. Retrieved 2016 - 07 - 29. Jump up ^ `` Howstuffworks `` 10 Amazing Telescopes '' ``. Science.howstuffworks.com. Archived from the original on December 22, 2008. Retrieved August 19, 2009. Jump up ^ SPIE 2006 in Orlando - Proceedings of SPIE conference 6267 on `` Ground - based and Airborne Telescopes '', `` The Large Binocular Telescope '', John M. Hill, Richard F. Green and James H. Slagle Jump up ^ `` The Carnegie Observatories -- Magellan Telescopes ''. Carnegie Institution for Science. Retrieved 2017 - 05 - 24. Jump up ^ The Telescope, By Geoff Andersen, Page 165 Jump up ^ ( 1 ) Archived July 22, 2011, at the Wayback Machine. Jump up ^ `` LAMOST Homepage -- Gallery ''. Lamost.org. August 13, 2012. Retrieved January 6, 2018. Jump up ^ Dwayne DayMonday, May 11, 2009 ( 2009 - 05 - 11 ). `` Mirrors in the dark ''. The Space Review. Retrieved 2012 - 01 - 03. CS1 maint : Multiple names : authors list ( link ) Jump up ^ Lowell Observatory - 4.3 - meter DCT Jump up ^ `` The Mayall 4 - Meter Telescope ''. Noao.edu. February 27, 1973. Retrieved August 19, 2009. Jump up ^ Sagar, Ram ; Brijesh Kumar ; Amitesh Omar ; A.K. Pandey ( 2012 ). `` New optical telescope projects at Devasthal Observatory ''. Proceedings of the Society of Photo - Optical Instrumentation Engineers. 8444. arXiv : 1304.2474. Bibcode : 2012SPIE. 8444E... 1TS. doi : 10.1117 / 12.925634. Jump up ^ `` Max - Planck - Institut für Astronomie ''. Mpia.de. July 20, 1994. Retrieved August 19, 2009. Jump up ^ John Pike. `` Starfire ''. Globalsecurity.org. Retrieved August 19, 2009. Jump up ^ `` NASA Orbital Debris Observatory ''. Astro.ubc.ca. Retrieved August 19, 2009. Jump up ^ `` Polissage Optique pour les Grands Instruments de la Physique et de l ' Astronomie '' ( PDF ). Archived from the original ( PDF ) on 2012 - 04 - 26. Jump up ^ `` Mirror Castings ''. Steward Observatory Mirror Lab. Jump up ^ `` Large Optics Manufacturing in Large Optics Manufacturing in Lytkarino Optical Glass Factory, Russia '' ( PDF ). Archived from the original ( PDF ) on 2012 - 04 - 26. Jump up ^ `` SUBARU Telescope 8.3 m Primary Mirror Finished ''. ^ Jump up to : `` Keck Telescope Facts ''. Spacecraftkits.com. Retrieved 2012 - 01 - 03. Jump up ^ `` Archived copy ''. Archived from the original on 2010 - 08 - 19. Retrieved 2010 - 08 - 16. ^ Jump up to : `` Telescope - Modern Optical Telescopes - Mirror, Diameter, Keck, and Honeycomb - JRank Articles ''. Science.jrank.org. Retrieved 2012 - 01 - 03. Jump up ^ K. Moskvitch - Four telescope link - up creates world 's largest mirror ( 2012 ) - BBC Jump up ^ KI Jump up ^ `` Large Telescopes ''. Astro.nineplanets.org. Retrieved 2012 - 01 - 03. Jump up ^ `` Groundbreaking for the E-ELT ( eso1419 -- Organisation Release ) ''. ESO. 19 June 2014. Retrieved 3 January 2015. Jump up ^ Stewart, Burnett, Colin M., John ( October 14, 2016 ). `` Hawaii Supreme Court voids Thirty Meter Telescope permit ''. Oahu Publications. West Hawaii Today. Retrieved 19 December 2015. Jump up ^ `` GMT -- Overview ''. Gmto.org. Retrieved 2017 - 05 - 24. Jump up ^ Amos, Jonathan ( 12 November 2015 ). `` Giant Magellan Telescope : Super-scope project breaks ground ''. BBC News. Retrieved 2015 - 11 - 15. Jump up ^ `` NASA 's Webb Observatory Requires More Time for Testing and Evaluation ; New Launch Window Under Review ''. NASA. 27 March 2018. Retrieved 29 March 2018. Jump up ^ `` International Liquid Mirror Telescope -- Extragalactic Astrophysics and Space Observations ''. Aeos.ulg.ac.be. Retrieved August 19, 2009. Jump up ^ CAPI Report ( in Spanish ). Nov. 4, 2013 Jump up ^ `` Introduction to the Chinese Giant Solar Telescope '' ( PDF ). Jump up ^ Staff ( 29 August 2012 ). `` China Exclusive : Scientists looking for site for giant solar telescope ''. Retrieved 8 December 2014. Further reading `` The Astronomical Scrapbook '', Joseph Ashbrook, Sky Publishing Corporation 1984, ISBN 0 - 933346 - 24 - 7, o `` Giant Telescopes of the World '', Sky and Telescope, August 2000. `` The History of the Telescope '', Henry C. King. ( 1955 ) `` The Historical Growth of Telescope Aperture '', René Racine, Publications of the Astronomical Society of the Pacific, 116 JRASC ( 1929 ) vol 23, p351 Sky&Telescope ( April 1981 ) p303 Sky&Telescope ( July 1993 ) vol 86, p 27 - 32 James H. Burge, 1993 Dissertation at UA, `` Advanced Techniques for Measuring Primary Mirrors for Astronomical Telescopes '' Bell, R.M. and Robins, G.C. and Eugeni, C. and Cuzner, G. and Hutchison, S.B. and Baily, S.H. and Ceurden, B. and Hagen, J. and Kenagy, K. and Martin, H.M. and Tuell, M. and Ward, M. and West, S.C. ( July 2008 ). `` LOTIS at completion of Collimator integration ''. Society of Photo - Optical Instrumentation Engineers ( SPIE ) Conference Series. 7017. doi : 10.1117 / 12.791889. CS1 maint : Multiple names : authors list ( link ) External links List of large reflecting telescopes The World 's Largest Optical Telescopes Largest optical telescopes of the world Selected largest telescopes Retrieved from `` https://en.wikipedia.org/w/index.php?title=List_of_largest_optical_reflecting_telescopes&oldid=833032896 '' Categories : Lists of telescopes Lists of superlatives Hidden categories : Webarchive template wayback links CS1 maint : Multiple names : authors list Talk Contents About Wikipedia Asturianu Català Čeština Deutsch Español فارسی Français Italiano Lëtzebuergesch Nederlands 日本 語 Português Svenska 中文 5 more Edit links This page was last edited on 29 March 2018, at 09 : 12. About Wikipedia

Question: where is the world's largest optical telescope located
Answer: Roque de los Muchachos Obs., Canary Islands, Spain