Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Extremely large telescope
open-in-new
<h2 id="list-of-telescopes">List of telescopes</h2> <table><tbody><tr><th>#</th><th>Image</th><th>Name</th><th>Aperture (m)</th><th>Area (m2)</th><th>Primary mirror</th><th>Altitude (m)</th><th>Firstlight</th><th>Notes</th><th>Refs</th></tr><tr><td>1</td><td></td><td><a href="/facts/European_Extremely_Large_Telescope/PCAY1z8l">Extremely Large Telescope</a>(ELT)</td><td>39.3</td><td>978</td><td>798 × 1.45 mhexagonal f/1</td><td>3060</td><td>2029</td><td>Under construction at <a href="/facts/Cerro_Armazones_Observatory/WTp7x8n0">Cerro Armazones Obs.</a>, Chile</td><td><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></td></tr><tr><td>2</td><td></td><td><a href="/facts/Thirty_Meter_Telescope/DcQASjGG">Thirty Meter Telescope</a>(TMT)</td><td>30.0</td><td>655</td><td>492 × 1.45 mhexagonal f/1</td><td>4050</td><td>Cancelled</td><td>Construction approved at <a href="/facts/Mauna_Kea_Observatory/UTo3GMuv">Mauna Kea Obs.</a> in Hawaii, USA, halted as of September 2019 due to protests</td><td><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></td></tr><tr><td>3</td><td></td><td><a href="/facts/Giant_Magellan_Telescope/A1g7gz9P">Giant Magellan Telescope</a>(GMT)</td><td>24.5</td><td>368</td><td>7 × 8.4 mcircular f/0.71</td><td>2516</td><td>2030s</td><td>Under construction at <a href="/facts/Las_Campanas_Observatory/6F9vgR2t">Las Campanas Obs.</a>, Chile;6/7 mirrors cast</td><td><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a><a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></td></tr><tr><td>4</td><td></td><td><a href="/facts/Large_Binocular_Telescope/UHHKIFAo">Large Binocular Telescope</a>(LBT)</td><td>11.8 (<i>equiv. area</i>)22.8 (<i>equiv. <a href="/facts/Diffraction/Mk80xXHT">detail</a> limit</i>)</td><td>111</td><td>2 × 8.4 mcircular</td><td>3221</td><td>2008</td><td>Largest non-segmented mirrors.Located on <a href="/facts/Mount_Graham/3tIgq5MX">Mount Graham</a>, Arizona, USA</td><td><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td></tr><tr><th colspan="10"><i>Note:</i> Aperture of LBT: the baseline is obtained via <a href="/facts/Aperture_synthesis/4gPMdmE1">aperture synthesis</a>.</th></tr></tbody></table> <h2 id="budget">Budget</h2> <p>Possible budget figures, which are estimates and can vary over time. For construction costs, it is recommended to estimate the cost of a giant telescope with the relation <i>cost</i> ∝ <i>D</i>2.7.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p> <table><tbody><tr><th>Name</th><th>Cost(est. USD)</th><th>Alternate</th></tr><tr><td><a href="/facts/European_Extremely_Large_Telescope/PCAY1z8l">Extremely Large Telescope</a> (ELT)</td><td>$1590 million</td><td>€1300 million<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></td></tr><tr><td><a href="/facts/Thirty_Meter_Telescope/DcQASjGG">Thirty Meter Telescope</a> (TMT)</td><td>$1400 million</td><td>$3600 million<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></td></tr><tr><td><a href="/facts/Giant_Magellan_Telescope/A1g7gz9P">Giant Magellan Telescope</a> (GMT)</td><td>$1000 million</td><td>$2540 million<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></td></tr><tr><td><a href="/facts/Large_Binocular_Telescope/UHHKIFAo">Large Binocular Telescope</a> (LBT)</td><td>$120 million</td><td></td></tr></tbody></table> <h2 id="projects">Projects</h2> <p>There were several telescopes in various stages in the 1990s and early 2000s, and some developed into construction projects. </p> Under construction <ul><li>ELT:<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> <a href="/facts/European_Extremely_Large_Telescope/PCAY1z8l">Extremely Large Telescope</a></li> <li>GMT:<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> <a href="/facts/Giant_Magellan_Telescope/A1g7gz9P">Giant Magellan Telescope</a></li></ul> Funded construction <ul><li>TMT:<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> <a href="/facts/Thirty_Meter_Telescope/DcQASjGG">Thirty Meter Telescope</a></li></ul> Projects <p>Some of these projects have been cancelled, or merged into ongoing extremely large telescopes. </p> <ul><li>GSMT:<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> Giant Segmented Mirror Telescope, merged into TMT</li> <li>OWL:<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> <a href="/facts/Overwhelmingly_Large_Telescope/MYYXqrHX">Overwhelmingly Large Telescope</a>, passed over in favor of ELT</li> <li>VLOT:<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> Very Large Optical Telescope, merged into TMT</li> <li>LAT:<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> Large Atacama Telescope</li> <li>EURO50:<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> European 50-metre Telescope, merged into ELT</li> <li>LPT:<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a> Large Petal Telescope</li> <li>Magellan 20: merged into <a href="/facts/Giant_Magellan_Telescope/A1g7gz9P">GMT</a></li> <li>HDRT:<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a> High Dynamic Range Telescope</li> <li>JELT:<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> Japanese ELT Project; Japan joined the TMT project in 2008</li> <li>CELT:<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> <a href="/facts/California_Extremely_Large_Telescope/fJaGP9M7">California Extremely Large Telescope</a>, became/merged into TMT</li> <li>MAXAT:<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> Maximum Aperture Telescope</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/List_of_largest_optical_reflecting_telescopes/15otBQpw">List of largest optical reflecting telescopes</a></li> <li><a href="/facts/List_of_telescope_types/mY8okufP">List of telescope types</a></li></ul> <h2 id="external-links">External links</h2> <ul><li> Media related to Extremely large telescopes at Wikimedia Commons</li> <li><a href="https://web.archive.org/web/20060825102344/http://www.aao.gov.au/instrum/ELT/Workshop/">Australian National Workshop on Extremely Large Telescopes (ELTs)</a></li> <li><a href="http://www.astro-opticon.org/fp5/ELT.html">The OPTICON ELT Working Group</a> a <a href="/facts/Europe/DTAtrKfh">Europe</a>-wide research project</li> <li><a href="https://web.archive.org/web/20120213001211/http://www.roe.ac.uk/ukatc/projects/elt/">The science case for Extremely Large Telescopes (ELTs)</a> from the <a href="/facts/Royal_Observatory%2c_Edinburgh/rh6Rht57">Royal Observatory, Edinburgh</a></li> <li><a href="https://web.archive.org/web/20200602141340/http://the-colossus.com/">Colossus Telescope</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>As A Skeleton Science Case For Extremely Large (20m–100m) Ground-based Telescopes (ELTs) and first section of ELT Roadmap Archived 2015-05-18 at the Wayback Machine, PDF <a href="http://www.astro-opticon.org/fp5/skelcase.html" target="_blank">http://www.astro-opticon.org/fp5/skelcase.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Overbye, Dennis (8 March 2024). "Good News and Bad News for Astronomers' Biggest Dream - The National Science Foundation takes a step (just one) toward an "extremely large telescope."". The New York Times. Archived from the original on 8 March 2024. Retrieved 8 March 2024. <a href="/wiki/Dennis_Overbye" target="_blank">/wiki/Dennis_Overbye</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Jha, Alok (5 August 2006). "Extremely Large Telescope could reveal secrets of life, the universe and everything". The Guardian. <a href="https://www.theguardian.com/science/2006/aug/05/spaceexploration.universe" target="_blank">https://www.theguardian.com/science/2006/aug/05/spaceexploration.universe</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Thirty Meter Telescope Construction Proposal" (PDF). TMT Observatory Corporation. 2007-09-12: 29. Archived from the original (PDF) on 2016-03-24. Retrieved 2009-07-24. {{cite journal}}: Cite journal requires |journal= (help) <a href="https://web.archive.org/web/20160324230243/http://tmt.org/news/TMT-Construction%20Proposal-Public.pdf" target="_blank">https://web.archive.org/web/20160324230243/http://tmt.org/news/TMT-Construction%20Proposal-Public.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Chapter 6: Optics" (PDF). GMT Conceptual Design Report. GMT Consortium. pp. 6–3. Retrieved 2008-04-02. <a href="http://www.gmto.org/codrfolder/GMT-ID-01467-Chapter_6_Optics.pdf" target="_blank">http://www.gmto.org/codrfolder/GMT-ID-01467-Chapter_6_Optics.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Groundbreaking for the E-ELT". 19 June 2014. <a href="http://www.eso.org/public/news/eso1419/" target="_blank">http://www.eso.org/public/news/eso1419/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Schilling, Govert (14 June 2011). "Europe Downscales Monster Telescope to Save Money". Science Insider. <a href="https://www.science.org/content/article/europe-downscales-monster-telescope-save-money" target="_blank">https://www.science.org/content/article/europe-downscales-monster-telescope-save-money</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"The E-ELT in numbers". Archived from the original on 2009-08-21. Retrieved 2009-08-11. <a href="https://web.archive.org/web/20090821225427/http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html" target="_blank">https://web.archive.org/web/20090821225427/http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Thirty Meter Telescope Construction Proposal" (PDF). TMT Observatory Corporation. 2007-09-12: 29. Archived from the original (PDF) on 2016-03-24. Retrieved 2009-07-24. {{cite journal}}: Cite journal requires |journal= (help) <a href="https://web.archive.org/web/20160324230243/http://tmt.org/news/TMT-Construction%20Proposal-Public.pdf" target="_blank">https://web.archive.org/web/20160324230243/http://tmt.org/news/TMT-Construction%20Proposal-Public.pdf</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Thirty Meter Telescope timeline page, TMT Observatory Project, archived from the original on 2010-09-25, retrieved 2010-10-12 <a href="https://web.archive.org/web/20100925013506/http://www.tmt.org/observatory/timeline" target="_blank">https://web.archive.org/web/20100925013506/http://www.tmt.org/observatory/timeline</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>TMT Timeline, accessed February 11, 2018 <a href="https://www.tmt.org/page/timeline?category=Observatory+Construction" target="_blank">https://www.tmt.org/page/timeline?category=Observatory+Construction</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Hawaii top court approves controversial Thirty Meter Telescope". BBC News. 31 October 2018. <a href="https://www.bbc.com/news/world-us-canada-46046864" target="_blank">https://www.bbc.com/news/world-us-canada-46046864</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Chapter 6: Optics" (PDF). GMT Conceptual Design Report. GMT Consortium. pp. 6–3. Retrieved 2008-04-02. <a href="http://www.gmto.org/codrfolder/GMT-ID-01467-Chapter_6_Optics.pdf" target="_blank">http://www.gmto.org/codrfolder/GMT-ID-01467-Chapter_6_Optics.pdf</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Howell, Elizabeth (29 December 2014). "Giant telescope gets $20m funding boost as design takes shape". Sen. Archived from the original on 17 July 2021. Retrieved 8 January 2015. <a href="https://web.archive.org/web/20210717164947/https://sen.com/news/giant-telescope-gets-20m-funding-boost-as-design-takes-shape" target="_blank">https://web.archive.org/web/20210717164947/https://sen.com/news/giant-telescope-gets-20m-funding-boost-as-design-takes-shape</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"Giant Magellan Telescope – 6th mirror cast". 12 March 2021. Retrieved 11 July 2023. <a href="https://www.universetoday.com/150506/the-giant-magellan-telescopes-6th-mirror-has-just-been-cast-one-more-to-go/" target="_blank">https://www.universetoday.com/150506/the-giant-magellan-telescopes-6th-mirror-has-just-been-cast-one-more-to-go/</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"Large Binocular Telescope Achieves First Binocular Light" (Press release). Large Binocular Telescope Corporation. 2008-02-28. Archived from the original on 2008-03-10. <a href="https://web.archive.org/web/20080310010642/http://medusa.as.arizona.edu/lbto/firstbinocularlight_press_release.htm" target="_blank">https://web.archive.org/web/20080310010642/http://medusa.as.arizona.edu/lbto/firstbinocularlight_press_release.htm</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Stepp, Larry; Daggert, Larry; Gillett, Paul. "Estimating the costs of extremely large telescopes" (PDF). National Optical Astronomy Observatory. <a href="http://www.gsmt.noao.edu/documentation/SPIE_Papers/Stepp.pdf" target="_blank">http://www.gsmt.noao.edu/documentation/SPIE_Papers/Stepp.pdf</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>"Funding boost for ESO's Extremely Large Telescope". The European Southern Observatory (ESO). Retrieved 29 August 2024. <a href="https://www.eso.org/public/announcements/ann20034/" target="_blank">https://www.eso.org/public/announcements/ann20034/</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>"NSF board approves funding for just one of two proposed giant telescopes". Science (Science.org). Retrieved 29 August 2024. <a href="https://www.science.org/content/article/nsf-board-approves-funding-just-one-two-proposed-giant-telescopes" target="_blank">https://www.science.org/content/article/nsf-board-approves-funding-just-one-two-proposed-giant-telescopes</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>"NSF board approves funding for just one of two proposed giant telescopes". Science (Science.org). Retrieved 29 August 2024. <a href="https://www.science.org/content/article/nsf-board-approves-funding-just-one-two-proposed-giant-telescopes" target="_blank">https://www.science.org/content/article/nsf-board-approves-funding-just-one-two-proposed-giant-telescopes</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>"Elt | Eso". <a href="http://www.eso.org/public/teles-instr/elt/" target="_blank">http://www.eso.org/public/teles-instr/elt/</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>"Giant Magellan Telescope". Giant Magellan Telescope. <a href="https://gmto.org/" target="_blank">https://gmto.org/</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>"TMT International Observatory". TIO. <a href="https://www.tmt.org/" target="_blank">https://www.tmt.org/</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>"AURA NIO: Home". October 19, 2006. Archived from the original on 2006-10-19. <a href="https://web.archive.org/web/20061019105956/http://www.aura-nio.noao.edu/" target="_blank">https://web.archive.org/web/20061019105956/http://www.aura-nio.noao.edu/</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>"The ESO 100-m OWL optical telescope concept". www.eso.org. <a href="https://www.eso.org/sci/facilities/eelt/owl/" target="_blank">https://www.eso.org/sci/facilities/eelt/owl/</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>"VLOT } The Very Large Optical Telescope for CI am Canada". May 2, 2009. Archived from the original on 2009-05-02. <a href="https://web.archive.org/web/20090502050342/http://www.hia-iha.nrc-cnrc.gc.ca/VLOT/" target="_blank">https://web.archive.org/web/20090502050342/http://www.hia-iha.nrc-cnrc.gc.ca/VLOT/</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>"Atacama". Archived from the original on 2003-12-02. Retrieved 2006-12-13. <a href="https://web.archive.org/web/20031202212639/http://astrosun.tn.cornell.edu/atacama" target="_blank">https://web.archive.org/web/20031202212639/http://astrosun.tn.cornell.edu/atacama</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>"Euro50". December 14, 2006. Archived from the original on 2006-12-14. <a href="https://web.archive.org/web/20061214083436/http://www.astro.lu.se/~torben/euro50/" target="_blank">https://web.archive.org/web/20061214083436/http://www.astro.lu.se/~torben/euro50/</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>"LPT | Large Petal Telescope". November 23, 2006. Archived from the original on 2006-11-23. <a href="https://web.archive.org/web/20061123185947/http://serweb.oamp.fr/denis/elt/ngcfht_may01.html" target="_blank">https://web.archive.org/web/20061123185947/http://serweb.oamp.fr/denis/elt/ngcfht_may01.html</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>https://home.ifa.hawaii.edu/users/kuhn/tmp.html%25%7Ctitle= 22 March 2002. <a href="https://home.ifa.hawaii.edu/users/kuhn/tmp.html%25%7Ctitle=" target="_blank">https://home.ifa.hawaii.edu/users/kuhn/tmp.html%25%7Ctitle=</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>http://optik2.mtk.nao.ac.jp/futureplan/eltproje.htm[permanent dead link] <a href="http://optik2.mtk.nao.ac.jp/futureplan/eltproje.htm" target="_blank">http://optik2.mtk.nao.ac.jp/futureplan/eltproje.htm</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>"index.html". June 5, 2002. Archived from the original on 2002-06-05. <a href="https://web.archive.org/web/20020605200532/http://celt.ucolick.org/" target="_blank">https://web.archive.org/web/20020605200532/http://celt.ucolick.org/</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>"MAXAT – the Maximum Aperture Telescope". Archived from the original on 6 July 2007. <a href="https://web.archive.org/web/20070706082910/http://www.gemini.edu/science/maxat/" target="_blank">https://web.archive.org/web/20070706082910/http://www.gemini.edu/science/maxat/</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> </ol>