CINXE.COM

<!DOCTYPE html> <html lang="en"> <head prefix="og: http://ogp.me/ns# fb: http://ogp.me/ns/fb#"><script type="text/javascript" src="/_static/js/bundle-playback.js?v=HxkREWBo" charset="utf-8"></script> <script type="text/javascript" src="/_static/js/wombat.js?v=txqj7nKC" charset="utf-8"></script> <script>window.RufflePlayer=window.RufflePlayer||{};window.RufflePlayer.config={"autoplay":"on","unmuteOverlay":"hidden"};</script> <script type="text/javascript" src="/_static/js/ruffle/ruffle.js"></script> <script type="text/javascript"> __wm.init("https://web.archive.org/web"); __wm.wombat("https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/","20170623140317","https://web.archive.org/","web","/_static/", "1498226597"); </script> <link rel="stylesheet" type="text/css" href="/_static/css/banner-styles.css?v=S1zqJCYt" /> <link rel="stylesheet" type="text/css" href="/_static/css/iconochive.css?v=3PDvdIFv" />  <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <base target="_top"/> <meta name="robots" content="index,follow"/> <meta name="author" content="information@eso.org"/> <meta name="description" content="ESO, European Organisation for Astronomical Research in the Southern Hemisphere"/> <meta name="keywords" content="ESO, eso.org, Astronomy, Astrophysics, Astronomie, Suedsternwarte, telescopes, detectors, comets, planets, stars, galaxies, nebulae, universe, NTT, VLT, VLTI, ALMA, ELT, La Silla, Paranal, Garching, Chile"/> <link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/" hreflang="x-default"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/australia/outreach/first-picture-of-a-black-hole/blog/" hreflang="en-au"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/unitedkingdom/outreach/first-picture-of-a-black-hole/blog/" hreflang="en-gb"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/ireland/outreach/first-picture-of-a-black-hole/blog/" hreflang="en-ie"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/usa/outreach/first-picture-of-a-black-hole/blog/" hreflang="en-us"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/albania/outreach/first-picture-of-a-black-hole/blog/" hreflang="sq"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/czechrepublic/outreach/first-picture-of-a-black-hole/blog/" hreflang="cs"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/denmark/outreach/first-picture-of-a-black-hole/blog/" hreflang="da"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/netherlands/outreach/first-picture-of-a-black-hole/blog/" hreflang="nl"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/belgium-nl/outreach/first-picture-of-a-black-hole/blog/" hreflang="nl-be"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/finland/outreach/first-picture-of-a-black-hole/blog/" hreflang="fi"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/france/outreach/first-picture-of-a-black-hole/blog/" hreflang="fr"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/belgium-fr/outreach/first-picture-of-a-black-hole/blog/" hreflang="fr-be"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/switzerland-fr/outreach/first-picture-of-a-black-hole/blog/" hreflang="fr-ch"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/germany/outreach/first-picture-of-a-black-hole/blog/" hreflang="de"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/austria/outreach/first-picture-of-a-black-hole/blog/" hreflang="de-at"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/belgium-de/outreach/first-picture-of-a-black-hole/blog/" hreflang="de-be"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/switzerland-de/outreach/first-picture-of-a-black-hole/blog/" hreflang="de-ch"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/greece/outreach/first-picture-of-a-black-hole/blog/" hreflang="el"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/iceland/outreach/first-picture-of-a-black-hole/blog/" hreflang="is"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/italy/outreach/first-picture-of-a-black-hole/blog/" hreflang="it"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/switzerland-it/outreach/first-picture-of-a-black-hole/blog/" hreflang="it-ch"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/norway/outreach/first-picture-of-a-black-hole/blog/" hreflang="nb"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/poland/outreach/first-picture-of-a-black-hole/blog/" hreflang="pl"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/brazil/outreach/first-picture-of-a-black-hole/blog/" hreflang="pt-br"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/portugal/outreach/first-picture-of-a-black-hole/blog/" hreflang="pt"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/russia/outreach/first-picture-of-a-black-hole/blog/" hreflang="ru"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/spain/outreach/first-picture-of-a-black-hole/blog/" hreflang="es"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/chile/outreach/first-picture-of-a-black-hole/blog/" hreflang="es-cl"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/serbia/outreach/first-picture-of-a-black-hole/blog/" hreflang="sr-latn"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/sweden/outreach/first-picture-of-a-black-hole/blog/" hreflang="sv"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/turkey/outreach/first-picture-of-a-black-hole/blog/" hreflang="tr"/><link rel="alternate" href="/web/20170623140317/https://www.eso.org/public/ukraine/outreach/first-picture-of-a-black-hole/blog/" hreflang="uk"/> <link rel="shortcut icon" href="https://web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/favicon.ico"/> <title>Taking the First Picture of a Black Hole | ESO</title> <link href="/web/20170623140317cs_/https://www.eso.org/public/archives/app/css/main.43b193fa1149.css" rel="stylesheet" type="text/css"/> <link href="https://web.archive.org/web/20170623140317/http://feeds.feedburner.com/EsoTopNews" rel="alternate" type="application/rss+xml" title="ESO Top News"/> <link href="https://web.archive.org/web/20170623140317/http://feeds.feedburner.com/EsoAnnouncements" rel="alternate" type="application/rss+xml" title="ESO Announcements"/> <link href="https://web.archive.org/web/20170623140317/http://feeds.feedburner.com/ESOcast" rel="alternate" type="application/rss+xml" title="ESOCast"/> <link href="https://web.archive.org/web/20170623140317/https://recruitment.eso.org/jobs.rss" rel="alternate" type="application/rss+xml" title="Jobs@ESO"/> <style type="text/css"> @font-face{ font-family:"Neue Helvetica W02_n4"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/88fcd49a-13c7-4d0c-86b1-ad1e258bd75d.d57caf27bb47.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W02"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/88fcd49a-13c7-4d0c-86b1-ad1e258bd75d.d57caf27bb47.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/88fcd49a-13c7-4d0c-86b1-ad1e258bd75d.d57caf27bb47.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/9a2e4855-380f-477f-950e-d98e8db54eac.071c48540fd7.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/fa82d0ee-4fbd-4cc9-bf9f-226ad1fcbae2.f18a0ab360b2.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/48d599a6-92b5-4d43-a4ac-8959f6971853.422c7c40cfe4.svg#48d599a6-92b5-4d43-a4ac-8959f6971853") format("svg"); font-weight: 400; font-style: normal; } @font-face{ font-family:"Neue Helvetica W02_i4"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/4d659910-cd87-42df-9427-0b30188ee52d.cb6898b0cbbf.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W02"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/4d659910-cd87-42df-9427-0b30188ee52d.cb6898b0cbbf.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/4d659910-cd87-42df-9427-0b30188ee52d.cb6898b0cbbf.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/ead34c63-62b9-4cbb-aff3-91ab2c130efc.6a712a9a7ea2.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/2cecf441-664d-4f6c-b76a-d5daddb1558f.688d1c31902e.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/72fa7506-a330-44d3-b365-a1f7524db90c.aef0d6fc2a64.svg#72fa7506-a330-44d3-b365-a1f7524db90c") format("svg"); font-weight: 400; font-style: italic; } @font-face{ font-family:"Neue Helvetica W02_n6"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/0b3a3fca-0fad-402b-bd38-fdcbad1ef776.4d1e3f9c0cc9.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W02"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/0b3a3fca-0fad-402b-bd38-fdcbad1ef776.4d1e3f9c0cc9.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/0b3a3fca-0fad-402b-bd38-fdcbad1ef776.4d1e3f9c0cc9.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/d5af76d8-a90b-4527-b3a3-182207cc3250.a6e2d3921c9e.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/1d238354-d156-4dde-89ea-4770ef04b9f9.c7d7d1136a4a.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/b68875cb-14a9-472e-8177-0247605124d7.8db29f59aad9.svg#b68875cb-14a9-472e-8177-0247605124d7") format("svg"); font-weight: 600; font-style: normal; } @font-face{ font-family:"Neue Helvetica W02_n7"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/55f60419-09c3-42bd-b81f-1983ff093852.c375031df0f9.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W02"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/55f60419-09c3-42bd-b81f-1983ff093852.c375031df0f9.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/55f60419-09c3-42bd-b81f-1983ff093852.c375031df0f9.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/5b4a262e-3342-44e2-8ad7-719998a68134.a93e96be336c.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/4a3ef5d8-cfd9-4b96-bd67-90215512f1e5.7f4a3911c966.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/58ab5075-53ea-46e6-9783-cbb335665f88.f6c3c719950c.svg#58ab5075-53ea-46e6-9783-cbb335665f88") format("svg"); font-weight: 700; font-style: normal; } @font-face{ font-family:"Neue Helvetica W10_n4"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/5b85c7cc-6ad4-4226-83f5-9d19e2974123.4fa9757217e7.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W10"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/5b85c7cc-6ad4-4226-83f5-9d19e2974123.4fa9757217e7.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/5b85c7cc-6ad4-4226-83f5-9d19e2974123.4fa9757217e7.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/835e7b4f-b524-4374-b57b-9a8fc555fd4e.05b343eeb1e1.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/2c694ef6-9615-473e-8cf4-d8d00c6bd973.6a1cc7710e71.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/3fc84193-a13f-4fe8-87f7-238748a4ac54.2dceb5842033.svg#3fc84193-a13f-4fe8-87f7-238748a4ac54") format("svg"); font-weight: 400; font-style: normal; } @font-face{ font-family:"Neue Helvetica W10_n6"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/f1feaed7-6bce-400a-a07e-a893ae43a680.fec704506841.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W10"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/f1feaed7-6bce-400a-a07e-a893ae43a680.fec704506841.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/f1feaed7-6bce-400a-a07e-a893ae43a680.fec704506841.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/8ac9e38d-29c6-41ea-8e47-4ae4d2b1a4e1.62a99c9560aa.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/4bd09087-655e-4abb-844c-dccdeb68003d.1c152e940e57.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/df234d87-eada-4058-aa80-5871e7fbe1c3.63935d690c36.svg#df234d87-eada-4058-aa80-5871e7fbe1c3") format("svg"); font-weight: 600; font-style: normal; } @font-face{ font-family:"Neue Helvetica W10_n7"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/7092fdcc-7036-48ce-ae23-cfbc9be2e3b0.3d35e366ffb4.eot#iefix") format("eot") } @font-face{ font-family:"Neue Helvetica W10"; src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/7092fdcc-7036-48ce-ae23-cfbc9be2e3b0.3d35e366ffb4.eot#iefix"); src:url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/7092fdcc-7036-48ce-ae23-cfbc9be2e3b0.3d35e366ffb4.eot#iefix") format("eot"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/5b29e833-1b7a-40ab-82a5-cfd69c8650f4.94335dd63f73.woff") format("woff"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/b0298148-2d59-44d1-9ec9-1ca6bb097603.5cf9c74c3265.ttf") format("truetype"),url("/web/20170623140317im_/https://www.eso.org/public/archives/app/fonts/fonts.net/ae1dea8c-a953-4845-b616-74a257ba72e6.6ef5c4edeb1b.svg#ae1dea8c-a953-4845-b616-74a257ba72e6") format("svg"); font-weight: 700; font-style: normal; } </style> <script type="text/javascript"> var MTIProjectId='02c4fda9-c362-4778-8957-ac86ff9054c6'; (function() { var mtiTracking = document.createElement('script'); mtiTracking.type='text/javascript'; mtiTracking.async='true'; mtiTracking.src=('https:'==document.location.protocol?'https:':'http:')+'//web.archive.org/web/20170623140317/https://fast.fonts.net/t/trackingCode.js'; (document.getElementsByTagName('head')[0]||document.getElementsByTagName('body')[0]).appendChild( mtiTracking ); })(); </script>  <meta name="twitter:card" content="summary"/> <meta name="twitter:site" content="@ESO"/> <meta name="twitter:creator" content="@ESO"/>  <script> window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date; ga('create', 'UA-1965004-1', 'auto'); ga('send', 'pageview'); </script> <script async src="//web.archive.org/web/20170623140317js_/https://www.google-analytics.com/analytics.js"></script>  <meta property="og:title" content="Taking the First Picture of a Black Hole"/> </head> <body> <nav class="navbar-general-wrapper" role="navigation"> <div class="navbar-general"> <div class="minilogo"> <a href="/web/20170623140317/https://www.eso.org/public/"> <div class="sprites-esologo-23-30" title="European Organisation for Astronomical Research in the Southern Hemisphere"></div> </a> </div> <div id="select-language"> <div class="flags"> <div title="Austria" class="sprites-flag_at"></div> <div title="Belgium" class="sprites-flag_be"></div> <div title="Czech Republic" class="sprites-flag_cz"></div> <div title="Denmark" class="sprites-flag_da"></div> <div title="Finland" class="sprites-flag_fi"></div> <div title="France" class="sprites-flag_fr"></div> <div title="Germany" class="sprites-flag_de"></div> <div title="Italy" class="sprites-flag_it"></div> <div title="Netherlands" class="sprites-flag_nl"></div> <div title="Poland" class="sprites-flag_pl"></div> <div title="Portugal" class="sprites-flag_pt"></div> <div title="Spain" class="sprites-flag_es"></div> <div title="Sweden" class="sprites-flag_sv"></div> <div title="Switzerland" class="sprites-flag_ch"></div> <div title="UK" class="sprites-flag_gb"></div> <div style="margin-left: 8px" title="Brazil" class="sprites-flag_br"></div> <div style="margin-left: 8px" title="Chile" class="sprites-flag_cl"></div> </div> <div class="languages"> <div class="language-button"> <span class="language-text">Select Language (en)</span> <div class="language-flag"><div title="en" class="flag sprites-flag_gb"> </div><span> (en)</span></div> <span class="caret"></span> </div> <ul class="languages-dropdown" role="menu"> <li class="language selected"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="International English" class="flag sprites-flag_en"> </div>International English</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/denmark/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Dansk" class="flag sprites-flag_da"> </div>Dansk</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/germany/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Deutsch" class="flag sprites-flag_de"> </div>Deutsch</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/belgium-de/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Deutsch (Belgien)" class="flag sprites-flag_be"> </div>Deutsch (Belgien)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/switzerland-de/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Deutsch (Schweiz)" class="flag sprites-flag_ch"> </div>Deutsch (Schweiz)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/austria/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Deutsch (Österreich)" class="flag sprites-flag_at"> </div>Deutsch (Österreich)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/australia/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="English (Australia)" class="flag sprites-flag_au"> </div>English (Australia)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/ireland/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="English (Ireland)" class="flag sprites-flag_ie"> </div>English (Ireland)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/unitedkingdom/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="English (UK)" class="flag sprites-flag_gb"> </div>English (UK)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/usa/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="English (USA)" class="flag sprites-flag_us"> </div>English (USA)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/spain/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Español" class="flag sprites-flag_es"> </div>Español</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/chile/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Español (Chile)" class="flag sprites-flag_cl"> </div>Español (Chile)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/france/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Français" class="flag sprites-flag_fr"> </div>Français</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/belgium-fr/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Français (Belgique)" class="flag sprites-flag_be"> </div>Français (Belgique)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/switzerland-fr/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Français (Suisse)" class="flag sprites-flag_ch"> </div>Français (Suisse)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/italy/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Italiano" class="flag sprites-flag_it"> </div>Italiano</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/switzerland-it/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Italiano (Svizzera)" class="flag sprites-flag_ch"> </div>Italiano (Svizzera)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/netherlands/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Nederlands" class="flag sprites-flag_nl"> </div>Nederlands</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/belgium-nl/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Nederlands (België)" class="flag sprites-flag_be"> </div>Nederlands (België)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/norway/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Norsk" class="flag sprites-flag_nb"> </div>Norsk</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/poland/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Polski" class="flag sprites-flag_pl"> </div>Polski</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/portugal/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Português" class="flag sprites-flag_pt"> </div>Português</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/brazil/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Português (Brasil)" class="flag sprites-flag_br"> </div>Português (Brasil)</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/albania/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Shqip" class="flag sprites-flag_sq"> </div>Shqip</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/serbia/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Srpski" class="flag sprites-flag_sr-latn"> </div>Srpski</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/finland/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Suomi" class="flag sprites-flag_fi"> </div>Suomi</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/sweden/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Svenska" class="flag sprites-flag_sv"> </div>Svenska</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/turkey/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Türkçe" class="flag sprites-flag_tr"> </div>Türkçe</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/iceland/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Íslenska" class="flag sprites-flag_is"> </div>Íslenska</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/czechrepublic/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Česky" class="flag sprites-flag_cs"> </div>Česky</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/russia/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="Русский" class="flag sprites-flag_ru"> </div>Русский</a></li> <li class="language"><a role="menuitem" href="/web/20170623140317/https://www.eso.org/public/ukraine/outreach/first-picture-of-a-black-hole/blog/?lang"><div title="українська" class="flag sprites-flag_uk"> </div>українська</a></li> </ul> </div> </div> <div class="sections"> <a href="/web/20170623140317/https://www.eso.org/sci/">Science</a> <a href="/web/20170623140317/https://www.eso.org/userportal/">User Portal</a> </div> <div class="searchbox"> <button type="button" class="btn btn-default" id="searchbox-button"> <span class="fa fa-search"></span> </button> <div id="searchbox-dropdown"> <form action="/web/20170623140317/https://www.eso.org/public/search/" method="get" class="form-inline" role="search"> <div class="form-group"> <div class="input-group"> <input type="text" value="" placeholder="Search..." name="q" class="form-control"> <span class="input-group-btn"> <button class="btn btn-default" type="submit"><span class="fa fa-search"></span></button> </span> </div>   </div> </form> </div> </div> <div class="links"> <a href="/web/20170623140317/https://www.eso.org/public/outreach/newsletters/esonews/">Subscribe</a> <a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/">Contact</a> <a href="/web/20170623140317/https://www.eso.org/public/sitemap/">Site Map</a> </div> </div> </nav> <nav class="main-menu-wrapper" role="navigation"> <div class="main-menu"> <div class="mobile-menu clearfix"> <button class="menu-trigger"><span class="fa fa-navicon"></span> Open Menu</button> </div> <ul class="level0 mainmenu-aim"> <li><a href="/web/20170623140317/https://www.eso.org/public/about-eso/">About<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-2" class="submenu-aim"> <li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/esoglance/"> ESO, the European Southern Observatory </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/organisation/"> Organisation </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/about-eso/dg-office/"> Director General <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-5" class="submenu-aim sublevel"><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/about-eso/dg-office/previous-dg/"> List of Directors General <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-6" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/dg-office/"> Prof. T. de Zeeuw </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/dg-office/ccesarsk/"> Dr. C. Cesarsky </a></li><li class=""><a class="no-link" href="#"> Prof. R. Giacconi </a></li><li class=""><a class="no-link" href="#"> Prof. H. van der Laan </a></li><li class=""><a class="no-link" href="#"> Prof. L. Woltjer </a></li><li class=""><a class="no-link" href="#"> Prof. A. Blaauw </a></li><li class=""><a class="no-link" href="#"> Prof. O. Heckmann </a></li></ul></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/committees.html"> ESO's Governing Bodies </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/"> Member States <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-15" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/austrianinvolvement/"> Austria </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/belgianinvolvement/"> Belgium </a></li><li class=""><a class="no-link" href="#"> Brazil </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/czechinvolvement/"> Czech Republic </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/danishinvolvement/"> Denmark </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/finnishinvolvement/"> Finland </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/frenchinvolvement/"> France </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/germaninvolvement/"> Germany </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/italianinvolvement/"> Italy </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/dutchinvolvement/"> Netherlands </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/polishinvolvement/"> Poland </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/portugueseinvolvement/"> Portugal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/spanishinvolvement/"> Spain </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/swedishinvolvement/"> Sweden </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/swissinvolvement/"> Switzerland </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/memberstates/britishinvolvement/"> United Kingdom </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/"> Travel and Contacts <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-32" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/garching/"> Travel to ESO Headquarters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/vitacura/"> Travel to Vitacura Office </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/guesthouse/"> Travel to Guesthouse </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/lasilla/"> Travel to La Silla </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/laserena/"> Travel to La Serena </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/paranal/"> Travel to Paranal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/antofagasta/"> Travel to Antofagasta </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/apexsequitor/"> Travel to APEX/Sequitor </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/chajnantor/"> Travel to Chajnantor </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/travel/elt/"> Travel to ELT Armazones </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/about-eso/visitors/"> Visits to ESO Sites <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-43" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/visitors/paranal/"> Weekend visits to Paranal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/visitors/lasilla/"> Weekend Visits to La Silla </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/visitors/alma/"> Public Visits to the ALMA OSF </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/pressmedia/mediavisits/"> Media Visits </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/visitors/tourist_and_students_form/"> Weekend Visits Form </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/architecture/"> Architecture at ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/collaborations/"> Collaborations with ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/acronyms/"> ESO Acronyms </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/timeline/"> Timeline </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/green/"> Green ESO </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/"> Frequently Asked Questions <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-54" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/faq-eso/"> ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/faq-eso-brazil/"> ESO & Brazil </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/faq-vlt-lasilla/"> VLT/La Silla </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/faq-apex-alma/"> APEX/ALMA </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/faq-survey-telescopes/"> Survey Telescopes </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/faq-elt/"> FAQ ELT </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/faq/privileges_and_immunities/"> Privileges and Immunities </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/about-eso/eso-and-chile/"> ESO & Chile </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/images/">Images<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-63" class="submenu-aim"> <li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/search/"> Advanced Search </a></li><li class="submenu"><a class="no-link children" href="#"> Categories <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-65" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/360pano/ "> 360 Panorama </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/alma/"> ALMA </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/apex/"> APEX </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/chile/"> Chile </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/cosmology/"> Cosmology </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/elt/"> ELT </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/eso-supernova/"> ESO Supernova </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/exoplanets/"> Exoplanets </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/fulldome/"> Fulldome </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/galaxies/"> Galaxies </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/galaxyclusters/"> Galaxy Clusters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/illustrations/"> Illustrations </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/lasilla/"> La Silla </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/nebulae/"> Nebulae </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/paranal/"> Paranal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/peopleandevents/"> People and Events </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/premises/"> Premises </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/blackholes/"> Quasars and Black Holes </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/solarsystem/"> Solar System </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/starclusters/"> Star Clusters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/stars/"> Stars </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/category/surveytelescopes/"> Survey Telescopes </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/comparisons/"> Image Comparisons </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/imageformats/"> Image Formats </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/images/potw/"> Picture of the Week <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-90" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2017/"> 2017 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2016/"> 2016 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2015/"> 2015 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2014/"> 2014 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2013/"> 2013 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2012/"> 2012 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2011/"> 2011 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2010/"> 2010 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2009/"> 2009 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2008/"> 2008 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/potw/archive/year/2007/"> 2007 </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/images/archive/top100/"> Top 100 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-102" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/archives/images/top100-large.zip"> Large JPG Zip File (1.9 GB) </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/archives/images/top100-original.zip"> Original TIF Zip File (32.9 GB) </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/copyright/"> Usage of ESO Images and Videos </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/wallpapers/"> Wallpapers </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/images/archive/zoomable/"> Zoomable </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/videos/">Videos<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-108" class="submenu-aim"> <li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/search/"> Advanced Search </a></li><li class="submenu"><a class="no-link children" href="#"> Categories <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-110" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/abouteso/"> About ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/alma/"> ALMA </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/apex/"> APEX </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/compilations/"> Compilations </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/cosmology/"> Cosmology </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/elt/"> ELT </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/esocast/"> ESOcast </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/events/"> Events </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/exoplanets/"> Exoplanets </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/featuremovies/"> Feature Movies </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/fulldome/"> Fulldome </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/galaxies/"> Galaxies </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/galaxyclusters/"> Galaxy Clusters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/lasilla/"> La Silla </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/nebulae/"> Nebulae </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/paranal/"> Paranal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/premises/"> Premises </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/blackholes/"> Quasars and Black Holes </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/solarsystem/"> Solar System </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/starclusters/"> Star Clusters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/stars/"> Stars </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videos/archive/category/vnr/"> Video News Releases </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/soft_subtitles/"> Subtitles and translations for ESO videos </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/copyright/"> Usage of ESO Videos and Images </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/videoformats/"> Video Formats </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/news/">News<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-136" class="submenu-aim"> <li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/news/"> Press Releases <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-137" class="submenu-aim sublevel"><li class="submenu"><a class="no-link children" href="#"> 2011–2017 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-138" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2017/"> 2017 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2016/"> 2016 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2015/"> 2015 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2014/"> 2014 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2013/"> 2013 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2012/"> 2012 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2011/"> 2011 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 2001–2010 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-146" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2010/"> 2010 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2009/"> 2009 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2008/"> 2008 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2007/"> 2007 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2006/"> 2006 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2005/"> 2005 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2004/"> 2004 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2003/"> 2003 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2002/"> 2002 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2001/"> 2001 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 1991–2000 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-157" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/2000/"> 2000 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1999/"> 1999 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1998/"> 1998 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1997/"> 1997 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1996/"> 1996 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1995/"> 1995 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1994/"> 1994 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1993/"> 1993 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1992/"> 1992 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1991/"> 1991 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 1985–1990 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-168" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1990/"> 1990 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1989/"> 1989 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1988/"> 1988 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1987/"> 1987 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1986/"> 1986 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/archive/year/1985/"> 1985 </a></li></ul></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/announcements/"> Announcements <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-175" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2017/"> 2017 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2016/"> 2016 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2015/"> 2015 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2014/"> 2014 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2013/"> 2013 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2012/"> 2012 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2011/"> 2011 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2010/"> 2010 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/archive/year/2009/"> 2009 </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/news/starsateso/"> Stars@ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/webupdates/"> New on eso.org </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/pressmedia/"> Press Room <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-187" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/broadcast/"> Broadcast Services </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/pressmedia/mediavisits/"> Media Visits </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/copyright/"> Copyright Notice </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/newsletters/"> ESO Newsletters <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-191" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/newsletters/esonews/"> ESO News </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/newsletters/outreach/"> ESO Outreach Community Newsletter </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/sci/publications/newsletter/"> ESO Science Newsletter </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/newsletters/#2"> ESO Media Newsletter </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/presscoverage/"> Press Coverage </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/shop/">ESOshop<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-197" class="submenu-aim"> <li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/shop/category/"> Shop Products <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-198" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/annualreport/"> Annual Reports </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/apparel/"> Apparel </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/book/"> Books </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/brochure/"> Brochures </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/calendar/"> Calendars </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/capjournal/"> CAPjournals </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/conferenceitem/"> Conferences </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/media/"> DVDs/Bluray/CDs </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/educationalmaterial/"> Educational Material </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/flyer/"> Flyers </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/handout/"> Handouts </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/map/"> Maps </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/merchandise/"> Merchandise </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/messenger/"> Messengers </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/mountedimage/"> Mounted Images </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/postcard/"> Postcards </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/printedposter/"> Posters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/technicaldocument/"> Reports </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/category/sticker/"> Stickers </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/cart/"> View shopping cart </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/checkout/"> Checkout </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/"> Information <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-220" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/archives/brochures/pdf/brochure_0040.pdf"> Catalogue </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/bulk_orders/"> Bulk Orders </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/"> Purchasing Steps </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/payment/"> Payment </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/shipping/"> Shipping </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/shopstaff/"> Staff Shopping </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shopinfo/terms/"> Terms & Conditions </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/freeorder/"> Free Orders for Educators and Media </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/">Telescopes & Instruments<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-229" class="submenu-aim"> <li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/"> Paranal Observatory <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-230" class="submenu-aim sublevel"><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/"> Very Large Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-231" class="submenu-aim sublevel"><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/"> VLT Instruments <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-232" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/4lgsf/"> 4LGSF </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/amber/"> AMBER </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/crires/"> CRIRES </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/espresso/"> ESPRESSO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/flames/"> FLAMES </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/fors/"> FORS1 and FORS2 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/gravity/"> GRAVITY </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/hawk-i/"> HAWK-I </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/isaac/"> ISAAC </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/kmos/"> KMOS </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/mad/"> MAD </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/midi/"> MIDI </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/muse/"> MUSE </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/naco/"> NACO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/naomi/"> NAOMI </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/pionier/"> PIONIER </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/sinfoni/"> SINFONI </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/sphere/"> SPHERE </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/uves/"> UVES </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/vimos/"> VIMOS </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/visir/"> VISIR </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/x-shooter/"> X-shooter </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-names/"> VLT Unit Telescopes Names <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-255" class="submenu-aim sublevel"><li class=""><a class="no-link" href="#"> ANTU </a></li><li class=""><a class="no-link" href="#"> KUEYEN </a></li><li class=""><a class="no-link" href="#"> MELIPAL </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-names/yepun/"> YEPUN </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/vlt/auxiliarytelescopes/"> Auxiliary Telescopes </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/"> Survey Telescopes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-261" class="submenu-aim sublevel"><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vista/"> VISTA <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-262" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vista/mirror/"> The VISTA mirror </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vista/camera/"> VIRCAM </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vista/4most/"> 4MOST </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vista/surveys/"> The VISTA surveys </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vista/consortium/"> The VISTA consortium </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vst/"> VST <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-268" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vst/mirror/"> The VST mirrors </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vst/camera/"> OmegaCAM </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vst/surveys/"> The VST surveys </a></li></ul></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/speculoos/"> SPECULOOS </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/paranal-observatory/ngts/"> NGTS </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/"> La Silla Observatory <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-274" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/swedish/"> Swedish–ESO Submillimetre Telescope </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/ntt/"> New Technology Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-276" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/ntt/efosc2/"> EFOSC2 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/ntt/emmi/"> EMMI </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/ntt/sofi/"> SOFI </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/36/"> ESO 3.6-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-280" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/36/harps/"> HARPS </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/mpg22/"> MPG/ESO 2.2-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-282" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/mpg22/grond/"> GROND </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/mpg22/wfi/"> WFI </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/swiss/"> Swiss 1.2-metre Leonhard Euler Telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/rem/"> Rapid Eye Mount telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/trappist/"> TRAnsiting Planets and PlanetesImals Small Telescope–South </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/danish154/"> Danish 1.54-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/tarot/"> Télescope à Action Rapide pour les Objets Transitoires </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/1mschmidt/"> ESO 1-metre Schmidt telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/152metre/"> ESO 1.52-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/1metre/"> ESO 1-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/05metre/"> ESO 0.5-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/coude/"> Coudé Auxiliary Telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/marly/"> MarLy 1-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/09metre/"> Dutch 0.9-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/t70/"> Swiss T70 telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/bochum/"> Bochum 0.61-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/danish05/"> Danish 0.5-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/gpo/"> Grand Prisme Objectif telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/swiss04/"> Swiss 0.4-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/marseille/"> Marseille 0.36-metre telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/grb/"> GRB Monitoring System </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/mascara/"> MASCARA </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/blackgem/"> BlackGEM </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/lasilla/extra/"> ExTrA </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/apex/"> APEX <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-307" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/apex/laboca/"> LABOCA </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/apex/sepia/"> SEPIA </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/alma/"> ALMA <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-310" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/alma/antennas/"> Antennas </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/alma/transporters/"> Transporters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/alma/interferometry/"> Interferometry </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/alma/residencia/"> ALMA Residencia </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/"> ELT <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-315" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_rev/"> Preparing a Revolution </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_exo/"> Are We Alone? </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_fir/"> First Objects </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_con/"> ELT Concept </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_euw/"> Window on the Universe </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_sit/"> Finding a Home </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt_num/"> ELT in numbers </a></li><li class="submenu"><a class="no-link children" href="#"> ELT Instruments <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-323" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt-instr/harmoni/"> HARMONI </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt-instr/maory/"> MAORY </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt-instr/metis/"> METIS </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/elt/elt-instr/micado/"> MICADO </a></li></ul></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/technology/"> Technology for Telescopes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-328" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/technology/active_optics/"> Active Optics </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/technology/adaptive_optics/"> Adaptive Optics </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/technology/ifu/"> Integral Field Units </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/technology/interferometry/"> Interferometry </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/teles-instr/technology/spectroscopy/"> Spectroscopy </a></li></ul></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/science/">Discoveries<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-334" class="submenu-aim"> <li class=""><a href="/web/20170623140317/https://www.eso.org/public/science/top10/"> ESO Top 10 Astronomical Discoveries </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/science/exoplanets/"> Exoplanets </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/science/stars/"> Very Old Stars </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/science/gc/"> Black Hole at the Centre of our Galaxy </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/science/grb/"> Gamma-Ray Bursts </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/science/archive/"> Science Archive </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/events/">Events<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-341" class="submenu-aim"> <li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/press-evt/"> Press Events </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/"> Special Events <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-343" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/announcements/ann16071/"> Open House Day 2016 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/MeetESO/"> #MeetESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse15/"> Long Night of Science 2015 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2014/"> ASTRONET 2014 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse14/"> Open House Day 2014 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/eeltblast/"> ELT Groundbreaking </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/cafe-and-kosmos/"> Café & Kosmos in Munich </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse13/"> Open House Day 2013 </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/"> ASTRONET 2013 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-352" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/dates/"> Important Dates </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/registration/"> Registration, Fees and Payment </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/abstracts/"> Abstract Submission </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/venue/"> Workshop Venue </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/practical_information/"> Practical Information </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/accommodation/"> Accommodation </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/organisers_partners/"> Organisers & Partners </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/contact/"> Contact </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/schedule/"> Schedule </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/astronet2013/participants/"> Participants </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/"> ESO 50 Years <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-363" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/message/"> Message from the DG </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/50highlights50years/"> Fifty Highlights </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/competitions/"> Competitions </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/twitter/"> Twitter Feed </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/webcast/"> Webcast </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/"> Europe to the Stars <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-369" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/news/"> News </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/movie/"> Movie </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/book/"> Book </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/reviews/"> Reviews </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/bios/"> Bios </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/offers/"> Purchase Offers </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/press/"> For the Press </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years/europetothestars/contact/"> Contact Us </a></li></ul></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/50years-in-chile/"> 50 years of ESO in Chile </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/awesome-universe/"> Awesome Universe <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-379" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/awesome-universe/venues/"> List of venues </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/awesome-universe/organisers/"> For Exhibitors </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/iya2009/"> IYA 2009 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/100ha/"> 100 Hours of Astronomy </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/theeye/"> The Eye 3D </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/imax-hidden-universe/"> IMAX® 3D Film Hidden Universe </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse11/"> Open House Day 2011 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse09/"> Open House Day 2009 (German) </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/bond/"> Bond at Paranal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/lndw-2007eng/"> Long Night of Science 2007 </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse/"> Open House Day 2006 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-390" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse/ohd06-winnerslist/"> List of Prize Winners </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse/tdot06/"> Deutsche Fassung </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/openhouse/tdot06-gewinnerliste/"> Liste der Preisgewinner </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/pt-011203/"> Public Talks 2003 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/special-evt/eso40years/"> ESO 40 Years (1962 - 2002) </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/exhibitions/"> Exhibitions <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-396" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/exhibitions/perma_exhibitions/"> ESO Permanent Exhibitions </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.esof.eu/"> EuroScience Open Forum (ESOF) </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://eas.unige.ch/EWASS2016/"> EWASS 2016 </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/https://aas.org/meetings/aas227"> AAS Winter 2016 </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/"> Astronomical Events <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-401" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/mcnaught2007/"> The Comet McNaught 2007 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/deepimpact/"> Deep Impact - 04.07.2005 </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.vt-2004.org/"> The Venus Transit - 08.11.2004 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/leonids99/"> The Leonids - 17.11.1999 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/eclipse99/"> Solar Eclipse at ESO HQ - 11.08.1999 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/leonids98/"> The Leonids - 11.1998 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/pathfinder/"> Mars Pathfinder - 1997 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/hyakutake/"> Comet Hyakutake - 1997 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/sl9/"> SL-9 and Jupiter - 1994 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/astro-evt/hale-bopp/"> Comet Hale Bopp - 1994 </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/events/seminars/"> Astronomy Communication Seminars </a></li> </ul> </div> </div> </li> <li class="current current-leaf"><a href="/web/20170623140317/https://www.eso.org/public/outreach/">Outreach<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-413" class="submenu-aim selected"> <li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/"> Education <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-414" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/education/"> Educational Material </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.scienceinschool.org/" target="_blank"> Science in School </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://sterrenlab.com/camps/eso-astronomy-camp-2014/"> Astronomy Camp 2014 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/teacherschools/"> Teacher Schools </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/prev-programmes/"> Previous Programmes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-419" class="submenu-aim sublevel"><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.eaae-astronomy.org/catchastar/cas2013"> Catch a Star 2013 </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.eaae-astronomy.org/catchastar/cas2011"> Catch a Star 2011 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/cas/cas2008/"> Catch a Star 2008 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/cas/cas2007/"> Catch a Star 2007 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/cas/cas2005/"> Catch a Star 2005 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/cas/cas2004/"> Catch a Star 2004 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/cas/cas2003/"> Catch a Star 2003 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/cas/cas2002/"> Catch a Star 2002 </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/liu/"> Life in the Universe </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/pos/"> Physics On Stage </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/eduoff/seaspace/docs/"> Sea & Space </a></li></ul></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://kids.alma.cl/?lang=en"> ALMA Kids </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.sterrenlab.com/camps/eso-astronomy-camp-2015/ "> ESO Astronomy Camp 2015 </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/"> Partnerships <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-433" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/translators/"> Volunteer Translators </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/eson/"> ESO Science Outreach Network </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/chile/"> Cooperative Projects in Chile </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/eso-ambassadors/"> ESO Outreach Ambassadors </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/organisations/"> ESO Outreach Partner Organisations </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/educators/"> Informal Educators </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://eso.us2.list-manage1.com/subscribe?u=c35dd77ef962de779092c970b&id=bd58d6ae8d"> Outreach Newsletter Form </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/photo-ambassadors/"> ESO Photo Ambassadors </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/partnerships/music-ambassadors/"> ESO Music Ambassadors </a></li></ul></li><li class=""><a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/"> Taking the First Picture of a Black Hole </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/communication-resources/"> Astronomy Communication Resources </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.spacetelescope.org/"> The Hubble Space Telescope </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/gems/"> Cosmic Gems </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/social/"> Social Media </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/ultra-high-definition/"> Ultra HD Expedition <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-448" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/ultra-high-definition/team/"> Meet our Heroes </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/ultra-high-definition/journey/"> Journey Schedule </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/ultra-high-definition/equipment/"> Equipment </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/ultra-high-definition/technology-partners/"> Technology Partners </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/ultra-high-definition/blog/"> Blog </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/for_planetariums/"> For Planetariums </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/webcams/"> Webcams </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/your_eso_pictures/"> Your ESO Pictures </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/astroprize/"> European Astronomy Journalism Prize </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/hiddentreasures/"> Hidden Treasures <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-458" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/hiddentreasures/rules/"> Hidden Treasures Rules </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/hiddentreasures/instructions/"> Hidden Treasures Instructions </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/hiddentreasures/science_archive/"> Hidden Treasures Form </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.flickr.com/groups/esohiddentreasures/"> Flickr Upload </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/outreach/department/"> Our Team <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-463" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/department/students/"> Students and Visitors </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/department/former-employees/"> Former Employees </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/department/volunteers/"> Volunteers </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://supernova.eso.org/join-us/"> Join us </a></li></ul></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://supernova.eso.org/"> ESO Supernova </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/art/"> Art at ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/outreach/data2dome/"> Data2Dome </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/products/">Products<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-471" class="submenu-aim"> <li class="submenu"><a class="no-link children" href="#"> Audiovisual and multimedia <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-472" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/models3d/"> 3D models </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/applications/"> Apps </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/media/"> DVDs and CDs </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/imaxfilms/"> IMAX movies </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/minisites/"> Mini-sites </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/music/"> Music </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/planetariumshows/"> Planetarium shows </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/presentations/"> Presentations </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/virtualtours/"> Virtual Tours </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> Periodicals <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-482" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/messengers/"> Messenger </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/capjournals/"> CAP Journal </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/schools/"> Science in School </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> Print products <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-486" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/annualreports/"> Annual Reports </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/books/"> Books </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/brochures/"> Brochures </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/bulletins/"> Bulletins </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/calendars/"> Calendars </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/conf_posters/"> Conference posters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/flyers/"> Flyers </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/handouts/"> Handouts </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/maps/"> Maps </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/presskits/"> Press kits </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/reports/"> Reports </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/postcards/"> Postcards </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/stickers/"> Stickers </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/print_posters/"> Printed posters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/papermodels/"> Paper models </a></li></ul></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/products/merchandise/"> Merchandise <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-502" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/merchandise/"> Merchandise </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/apparel/"> Apparel </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/mountedimages/"> Mounted images </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/stationery/"> Stationery </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> Electronic products <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-507" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/electroniccards/"> Electronic cards </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/elec_posters/"> Electronic posters </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/epublications/"> ePublications </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/education/"> Educational material </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/exhibitions/"> Exhibition material </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/products/logos/"> Logos </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/shop/"> Order in ESOshop </a></li> </ul> </div> </div> </li> <li><a href="/web/20170623140317/https://www.eso.org/public/industry/">Business@ESO<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-515" class="submenu-aim"> <li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/cp.html"> Procurement at ESO </a></li><li class=""><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/industry/events/"> Industry Events </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/industry/techtrans/"> Technology Transfer <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-518" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/techtrans/technology-developed-by-industry-or-institutes/"> Technology Developed by Industries </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/techtrans/develeso/"> Novel technologies by ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/techtrans/developments/"> ESO know-how </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/projects.html"> Future Projects </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/industry/safety.html"> Safety <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-523" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/safety/emergency.html"> Emergency & Evacuation </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/safety/traffic.html"> Traffic & Parking at ESO </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/safety/contractors.html"> Contractors at ESO </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/industry/contact/"> Contact Information </a></li> </ul> </div> </div> </li> <li><a href="https://web.archive.org/web/20170623140317/https://recruitment.eso.org/">Jobs<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-528" class="submenu-aim"> <li class=""><a href="https://web.archive.org/web/20170623140317/https://recruitment.eso.org/"> Recruitment </a></li><li class="submenu"><a href="/web/20170623140317/https://www.eso.org/public/jobs/conditions/"> Employment Conditions <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-530" class="submenu-aim sublevel"><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/conditions/intstaff/"> International Staff Members </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/conditions/fellows/"> Fellows </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/conditions/students/"> Students </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/conditions/paidassoc/"> Paid Associates/Others </a></li></ul></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/pes/"> Human Resources </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/grants/"> Grants </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/how_to_use/"> How to use this site </a></li><li class=""><a href="/web/20170623140317/https://www.eso.org/public/jobs/terms/"> Site Terms </a></li> </ul> </div> </div> </li> </ul> </div> </nav> <div id="content"> <div id="eso-side-logo"> <a href="/web/20170623140317/https://www.eso.org/public/"> <div data-spy="affix" class="affix"> <div class="sprites-esologo"></div> <span>European<br>Southern<br>Observatory</span> </div> </a> </div> <div class="container" id="body"> <div class="row no-page"> <div class="col-md-12"> </div> </div> <div class="row page"> <div class="col-md-12 one-column"> <div id="edit-info-block"> <div id="page-edit-success" class="alert alert-success alert-dismissible" role="alert" style="display: none"> <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">×</span></button> Page saved successfully </div> <div id="page-edit-failure" class="alert alert-danger alert-dismissible" role="alert" style="display: none"> <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">×</span></button> Couldn't save page :( Please try again. </div> </div> <div class="page-content"> <div id="editable-content">  <div id="fb-root"></div> <script>(function(d, s, id) { var js, fjs = d.getElementsByTagName(s)[0]; if (d.getElementById(id)) return; js = d.createElement(s); js.id = id; js.src = "//web.archive.org/web/20170623140317/https://connect.facebook.net/en_GB/sdk.js#xfbml=1&version=v2.8"; fjs.parentNode.insertBefore(js, fjs); }(document, 'script', 'facebook-jssdk'));</script>  <h1>Taking the First Picture of a Black Hole</h1> <div style="margin: 40px auto"><a class="anchor" name="17062001"></a><h2>5. How to build an Earth-sized radio telescope</h2> <div style="font-family: Helvetica, Arial, sans-serif; font-size: x-small; color: #4f4f4f;">20.6.2017</div></div> <p>A <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Black_hole">black hole</a> is an extraordinary object with extremely strong gravity, but when observed from Earth it would look like a tiny dot. To capture an image of a black hole, a telescope with extraordinarily high resolution is required. But how can such a revolutionary telescope be created?</p> <p>As we discovered in the previous post, the larger the diameter of the telescope, the better the resolution. This is true both for optical and radio telescopes, which means that a tremendously large telescope is needed to observe a small object that can barely be seen from Earth — like a black hole.</p> <p>The <a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/teles-instr/alma/">Atacama Large Millimeter/submillimeter Array</a> (ALMA), which is operated in Chile by a global partnership, combines multiple antennas spread over distances from 150 metres to 16 kilometres. This allows it to simulate a single giant telescope much larger than any individual dish that could be built, achieving a resolution equivalent to up to a 16-km diameter telescope. ALMA’s resolution reaches 1/100 of 1/3600 of a degree angle — 5000 times better than the human eye! </p> <p>And yet even with such an exceptionally good “eyesight”, ALMA would need to improve its resolution 100 fold in order to capture a black hole at the centre of the Milky Way galaxy.</p> <p>To simulate a telescope with 100 times the resolution of ALMA, telescopes must be spread over a much larger area — far beyond the Chilean Andes, beyond even South America and extending to North America and Europe. Using the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Very-long-baseline_interferometry">Very-Long-Baseline Interferometry</a> (VLBI) technique, telescopes of several thousand kilometres in diameter can be simulated. The <a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope</a> (EHT) and <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">Global mm-VLBI Array</a> (GMVA) both form Earth-sized telescopes that combine the observing power and the data collected by a range of telescopes across the world, including ALMA. The participating telescopes are listed below. </p> <table width="70%"> <tr> <td width="15%"><b>Project</b></td> <td width="85%"><b>Contributing Telescopes</b></td> </tr> <tr> <td width="15%">EHT</td> <td width="85%">ALMA, APEX (Chile), JCMT, SMA (Hawaii, US), ARO/SMT (Arizona, US), LMT(Mexico), IRAM 30m (Spain), NOEMA (France), SPT (South Pole)</b></td> </tr> <tr> <td width="15%">GMVA</td> <td width="85%">ALMA, VLBA (eight locations in U.S.), GBT 100m (West Virginia, U.S.), IRAM 30m (Spain), OAN 40m (Spain), Max Planck Institute for Radio Astronomy 100m (Germany)</b></td> </tr> </table> <div style="width: 80%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/eht_with_title_30march/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eht_with_title_30march.jpg" alt="EHT infographic"></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Telescopes contributing to the EHT and GMVA observations of Sagittarius A*. The connected telescopes simulate a telescope equivalent to the dimensions of the whole western hemisphere of the Earth. Credit: ESO/O. Furtak</em></div> </div> <p>But how does VLBI work? With ALMA, it’s relatively straightforward: each antenna receives signals from a target object and then sends them via optical fibres to a central location on site, where they are processed and combined by a dedicated supercomputer. However, when telescopes are located thousands of kilometres apart — halfway across the world from each other — it’s impossible to connect them via optical fibres to a central location and transmit such enormous volumes of data. VLBI therefore uses a different technique: the data are first recorded at each individual telescope and stored on recording devices on site. These devices are then shipped or flown back to one place and played back all together in a computer for data synthesis. </p> <div style="width: 60%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/eht-infography/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eht-infography.jpg" alt="A schematic diagram of the VLBI mechanism."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>A schematic diagram of the VLBI mechanism. Each antenna, spread out over vast distances, has an extremely precise atomic clock. Analogue signals collected by the antenna are converted to digital signals and stored on hard drives together with the time signals provided by the atomic clock. The hard drives are then shipped to a central location to be synchronised. An astronomical observation image is obtained by processing the data gathered from multiple locations. Credit: ALMA (ESO/NAOJ/NRAO), J.Pinto & N.Lira.</em></div> </div> <p>A key component of the VLBI technique are the clocks — and these are no ordinary clocks. To synthesise the data gathered simultaneously by contributing telescopes around the world, each telescope requires a clock set to the accurate time with astonishing precision. These clocks measure small differences in the arrival time of the radio waves coming from the target object to each antenna of the array. Every telescope taking part in VLBI is equipped with an extremely precise, specially-developed atomic clock — so accurate that over a period of 100 million years, each clock would be off by less than 1 second! </p> <div style="width: 80%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/140604_almamaser_05/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/140604_almamaser_05.jpg" alt="Hydrogen maser atomic clock installed at the ALMA AOS."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Hydrogen maser atomic clock installed at the ALMA Array Operations Site (AOS), along with the technicians who installed it. Credit: ALMA (ESO/NAOJ/NRAO), C. Padilla.</em></div> </div> <p>Another key element in VLBI is the device used to record the data. The first VLBI experiments were carried out in the 1960s and used <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Magnetic_tape_data_storage">magnetic tapes</a> to record observations, but since entering the 21st century, more and more VLBI observations have been recorded on hard drives because of their larger storage capacity and lower prices. The hard drives used in the EHT and GMVA observations are based on magnetic-disk technology and incorporate primarily low-cost PC components.</p> <p>One important aspect of such a recording device is the speed with which it records data. The faster the data recording speed, the more extensive the range of frequency signals that can be recorded, which improves the overall sensitivity of the observations. Some of the hard drives used in the EHT observations can record data at up to a total rate of 16 <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Bit_rate">gigabits per second</a>! Of course, the storage capacity of the hard drives is also important. The capacity of the hard drives ALMA used for the EHT/GMVA observations exceeds 1 petabyte (1 million gigabytes) in total.</p> <p>The dedicated supercomputer to process the recorded data is called a “correlator”. The EHT correlator was developed by the Massachusetts Institute of Technology in the US, while the GMVA correlator was developed by the Max Planck Institute for Radio Astronomy located in Bonn, Germany. The enormous amount of data obtained is firstly recorded at the telescopes around the world, and then sent to these two locations where it is read from each disk to the correlator at up to 4096 MB per second. The data is then processed by the correlator to form an astronomical image.</p> <p>The VLBI technique can use these cutting-edge technologies to form an Earth-sized telescope capable of achieving extremely high resolution. This raises the question: Can any type of celestial object be revealed in detail by VLBI observations? Unfortunately, the answer is no. Some objects will be a good target of the VLBI observations, while others will not.</p> <p>If you’ve ever used a microscope to observe a small object, you might be familiar with the experience of raising the magnification — only to see a dimmer view. The same thing happens with telescopes. Increasing the resolution means seeing an object in a view that is divided into many smaller parts. This inevitably results in decreasing the amount of light received from each part of the target object. Eventually, as the resolution increases, fainter objects becomes invisible.</p> <p>For this reason, the extraordinarily high resolution of VLBI is mainly suitable for observing bright objects. VLBI is often used to observe objects that emit intense radio waves, such as astrophysical <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Maser#Astrophysical_masers">masers</a> (similar to the kind of lasers that we are familiar with, but at microwave wavelengths) occurring around young and old stars, and high-speed <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Astrophysical_jet">jets</a> of gas ejected from supermassive black holes. Since a high-temperature gas disk around a supermassive black hole is thought to emit strong radio waves, the EHT and GMVA observations aim to use the VLBI technique to capture the elusive black hole at the centre of the galaxy. </p> <p>This is the fifth post of a blog series following the <a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope</a> and the <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">Global mm-VLBI Array</a> projects. The next topic will focus on the supermassive black hole Sagittarius A* located at the centre of the Milky Way, a high-priority target object of the EHT/GMVA observations. </p> <h3>Links</h3> <ul> <li><a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Read more about ALMA</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">GMVA website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/social/">Connect with ESO on social media</a> for more exciting updates about this ambitious project.</li> </ul> <div class="fb-like" data-href="https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17062001" data-layout="standard" data-action="like" data-size="small" data-show-faces="true" data-share="true"></div> <div> <br> <a href="https://web.archive.org/web/20170623140317/https://twitter.com/share" class="twitter-share-button" data-text="How to build an Earth-sized radio telescope #AttemptingTheImpossible #FirstPictureOfBlackHole" data-url="https://web.archive.org/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17062001" data-show-count="true">Tweet</a><script async src="//web.archive.org/web/20170623140317js_/https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> </p> <hr> <p> </p> <div style="margin: 40px auto"><a class="anchor" name="17052301"></a><h2>4. How do Radio Telescopes work?</h2> <div style="font-family: Helvetica, Arial, sans-serif; font-size: x-small; color: #4f4f4f;">23.5.2017</div></div> <p>Can you imagine yourself hearing only the bass of a music recording? Or only seeing objects of a particular colour? Well, in a way, you experience this every day. The human eye can only detect a narrow part of the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Electromagnetic_spectrum">electromagnetic spectrum</a>: a section we call visible <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Light">light</a>. But a broad range of electromagnetic waves exist with the same nature — for example radio waves, which have much longer wavelengths than the light we can detect with our eyes. Radio wavelengths range from 1 millimetre to over 10 metres, while visible light wavelengths are only a few hundred <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Nanometre">nanometres</a> — one nanometre is 1/10 000th the thickness of a piece of paper!</p> <p><a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Radio_wave">Radio waves</a> are not visible to us directly, but in 1867 their existence was predicted by James Clerk Maxwell. By the end of the 19th century, scientists had developed instruments that could transmit and detect electromagnetic waves at the radio end of the spectrum. A few decades later, it was discovered that these instruments could not only be used for communication, but could also be directed towards space — hidden parts of the Universe were suddenly revealed!</p> <p>The first detection of radio waves from an astronomical object was in 1932, when Karl Jansky observed radiation coming from the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Radio_astronomy">Milky Way</a>. Then came the phenomenal discovery of the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Cosmic_microwave_background">cosmic microwave background</a> in 1964, worthy of a Nobel Prize in Physics. Soon afterwards, <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Jocelyn_Bell_Burnell">Jocelyn Bell Burnell</a> observed the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/PSR_B1919%2B21">first pulsar</a> with an array of radio aerials in 1967, which led to another Nobel Prize. And this was only the beginning — a dazzling array of discoveries have been made since.</p> <div style="width: 80%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/potw1150a/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/potw1150a.jpg" alt="ALMA's world at night."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>This panoramic view of the Chajnantor plateau shows some of the 66 antennas of the Atacama Large Millimeter/submillimeter Array (ALMA). Credit: ESO/B. Tafreshi (<a href="https://web.archive.org/web/20170623140317/http://twanight.org/">twanight.org</a>)</em></div> </div> <p>But how do radio telescopes work?</p> <p>In order to detect signals from astronomical objects, every radio telescope requires an antenna and at least one receiver. They come in a variety of shapes and sizes, reflecting the need to be able to detect a great breadth of radio waves across many wavelengths. </p> <p>The antennas of most radio telescopes working at wavelengths shorter than 1 metre are <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Parabolic_antenna">paraboloidal dishes</a>. The curved reflector concentrates incoming radio waves at a focal point. For shorter wavelengths, such as millimetre waves collected by <a href="https://web.archive.org/web/20170623140317/http://www.almaobservatory.org/">ALMA</a> and <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Very-long-baseline_interferometry">VLBI</a> networks like the <a href="https://web.archive.org/web/20170623140317/http://www.eventhorizontelescope.org/">EHT</a> and <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/index.html">GMVA</a>, the perfection of the dish’s surface is critical: any warp, bump, or dent in the parabola will scatter these tiny waves away from the focus, and valuable information is lost.</p> <p>In addition to the main dish, most radio telescopes have secondary reflectors that send the concentrated waves to receivers. These receivers select, detect and amplify the radio signals of the desired frequencies. The receiver delivers these signals in an analogue format, which is converted into a digital signal and fed into a computer. Astronomers can then stitch these signals together to create a map of the sky measured by radio brightness.</p> <p>Radio telescopes point at a radio source for hours in order to detect the faintest signals coming from the near and distant Universe. This technique is a similar to keeping the shutter of a camera open for a long exposure at night. After combining these signals with a computer, astronomers can analyse the radiation emitted by many astronomical phenomena — such as stars, galaxies, nebulae and supermassive black holes.</p> <div style="width: 80%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/galactic_center_hi/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/galactic_center_hi.jpg" alt="The galactic centre."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>The view of the centre of our galaxy with a closer view of the object known as Sagittarius A*, the bright radio source that corresponds to the supermassive black hole. Credit: NRAO/AUI/NSF</em></div> </div> <p>Here’s the problem in radio astronomy: because radio wavelengths are so long, it is difficult to achieve a high <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Angular_resolution">resolution</a> of the objects being observed. Even the shortest radio wavelengths observed by the largest single telescopes only result in an angular resolution slightly better than that of the unaided eye. The resolution (or degree of detail in the image) of a single telescope can be calculated by dividing the length of the radio wave by the diameter of the antenna. When this ratio is small, the angular resolution is large and therefore finer details can be observed. The larger the diameter of the telescope, the better the resolution, therefore radio telescopes tend to be much larger than telescopes suited for other, shorter wavelengths like visible light.</p> <p>The longest wavelengths, on scales of metres, pose a particular challenge because it is hard to achieve good resolution from a single dish. The largest moveable dish is the <a href="https://web.archive.org/web/20170623140317/http://greenbankobservatory.org/">Green Bank Telescope</a> (100 metres across). Dishes that don’t move can be much, much larger. The world's biggest radio dish is the newly-constructed <a href="https://web.archive.org/web/20170623140317/http://fast.bao.ac.cn/en/">Five-hundred-meter Aperture Spherical Telescope</a> (FAST) in China: a fixed dish supported by a natural basin in the landscape. FAST can observe radio waves up to 4.3 metres in wavelength. There are also other similar dishes, such as the historic 300-metre <a href="https://web.archive.org/web/20170623140317/http://www.naic.edu/">Arecibo Observatory</a>, which was the largest telescope for five decades until FAST was completed in 2016.</p> <p>But building antennas any larger than this is not feasible, so here we reach a limit when it comes to observing at longer and longer wavelengths. But what <em>can</em> be improved is the angular resolution, opening the door of investigation into the finest details of the low-energy Universe.</p> <p>A Nobel Prize winning technique called interferometry opened this door: if the signals from many antennas spread over a large area are combined, then the antennas can operate together like a gigantic telescope — an array. Modern arrays usually bring the signals together at a central location in digital form using optical fibres, and then process them in a special-purpose supercomputer called a correlator.</p> <div style="width: 80%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/eso1312a/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eso1312a.jpg" alt="ALMA array from the air."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>An aerial view of the Chajnantor plateau, located at an altitude of 5000 meters in the Chilean Andes, where the array of ALMA antennas is located. Credit: Clem & Adri Bacri-Normier (<a href="https://web.archive.org/web/20170623140317/http://wingsforscience.com/">wingsforscience.com</a>)/ESO</em></div> </div> <p>One such array is the <a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Atacama Large Millimeter/submillimeter Array</a> on the Chajnantor plateau in the Atacama Desert. ALMA comprises 66 high-precision antennas up to 16 kilometres apart, working together as an <a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/teles-instr/alma/interferometry/">interferometer</a>. The resolution of an interferometer depends not on the diameter of individual antennas, but on the maximum separation between them. Moving the antennas further apart increases the resolution. </p> <p>The signals from the antennas are brought together and processed by the ALMA correlator. The antennas work together in unison, giving ALMA a maximum resolution which is even better than that achieved at visible wavelengths by the NASA/ESA Hubble Space Telescope. This is because the maximum distance between the antennas can be very large, increasing the resolving power of the interferometer and allowing it to detect smaller details. </p> <p>The ability to link antennas over baselines of many kilometres is crucial to obtain extremely good resolution and a high degree of detail in the images. This gives astronomers the possibility to go even further than arrays like ALMA; by combining the signals from radio telescopes all across the world, the distances between the antennas can be Earth-sized — and even larger, in the case of space-based antennas like <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Spektr-R">Spektr-R</a>. </p> <p>The telescopes do not have to be physically connected; rather, the signals recorded at each telescope are later “played back” in the correlator. This technique, called <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Very-long-baseline_interferometry">very-long-baseline interferometry</a> (VLBI), provides exquisite angular resolution and paves the way for phenomenal new discoveries — including the detailed observation of the supermassive black hole at the centre of our galaxy.</p> <p>This is the fourth post of a blog series following the <a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope</a> and the <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">Global mm-VLBI Array</a> projects. Next time, we’ll talk about how to build an Earth-sized radio telescope.</p> <h3>Links</h3> <ul><li><a href="https://web.archive.org/web/20170623140317/https://public.nrao.edu/telescopes/radio-telescopes">Read more about radio telescopes</a></li> <li><a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Read more about ALMA</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.almaobservatory.org/en/press-room/announcements-events/900-alma-links-with-other-observatories-to-create-earth-size-telescope">Find out more about ALMA’s VLBI capabilities</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">GMVA website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/social/">Connect with ESO on social media</a> for more exciting updates about this ambitious project.</li></ul> <div class="fb-like" data-href="https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17052301" data-layout="standard" data-action="like" data-size="small" data-show-faces="true" data-share="true"></div> <div> <br> <a href="https://web.archive.org/web/20170623140317/https://twitter.com/share" class="twitter-share-button" data-text="How do Radio Telescopes work? #AttemptingTheImpossible #FirstPictureOfBlackHole" data-url="https://web.archive.org/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17052301" data-show-count="true">Tweet</a><script async src="//web.archive.org/web/20170623140317js_/https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> </p> <hr> <p> </p> <div style="margin: 40px auto"><a class="anchor" name="17050201"></a><h2>3. What’s so interesting about the event horizon?</h2> <div style="font-family: Helvetica, Arial, sans-serif; font-size: x-small; color: #4f4f4f;">2.5.2017</div></div> <p>We know that black holes are fascinating objects, capable of bending not only our minds but also reality itself. They squeeze matter into an extraordinarily miniscule space, resulting in an object with an immense gravitational pull. Around this object is a boundary beyond which nothing can escape, not even light: the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Event_horizon">event horizon</a>. Besides attracting enormous quantities of matter, the event horizon is attracting a lot of attention from astronomers around the world. But why?</p> <p>As we discovered in the previous post, black holes are impossible to observe directly. <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Photon">Photons</a> aren’t emitted, and therefore nothing reaches the astronomer’s telescope (except, of course, small amounts of <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Hawking_radiation">Hawking radiation</a>). But scientists can learn a lot from the bright material surrounding black holes. </p> <p>When matter comes under the gravitational spell of a black hole, material will either be sucked directly into it or will be pulled into a doomed orbit like water circling a drain. The gravitational pull near the event horizon is so strong that the matter around it reaches relativistic speeds (i.e. speeds comparable to the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Speed_of_light">speed of light</a>). The friction between the material heats it to incredibly high temperatures, turning it into glowing <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Plasma_(physics)">plasma</a>. Close to the event horizon photons are pulled into nearly circular orbits, and this form a bright photon ring which outlines the black “shadow” of inside the event horizon itself. </p> <div style="width: 80%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/raptor-4k/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/raptor-4k.jpg" alt="Simulated image of an accreting black hole."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Simulated image of an accreting black hole. The event horizon is in the middle of the image, and the shadow can be seen with a rotating accretion disk surrounding it. Credit: Bronzwaer/Davelaar/Moscibrodzka/Falcke/Radboud University</em></div> </div> <p>Einstein’s theory of <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/General_relativity">general relativity</a> predicts the existence of event horizons around black holes. But until now, the resolution of our telescopes has not been high enough to “see” a black hole. Despite the fact that the event horizon can be millions of kilometres in diameter, black holes are elusive. They are very far away and often hidden behind significant amounts of interstellar gas and dust. At 26 000 light-years from Earth, our galaxy’s supermassive black hole — called <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Sagittarius_A*">Sagittarius A*</a> — is just a tiny pinprick on the sky.</p> <p>By linking up different telescopes across the globe, the <a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope</a> (EHT) and the <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">Global mm-VLBI Array</a> (GMVA) can achieve the resolution necessary to perceive the pinprick of Sagittarius A*. Without doubt, these observations are incredibly exciting. They will allow for the study of black holes in more detail — as well as acting as a test for Einstein’s theory of General Relativity.</p> <p><em>“Einstein's wonderful general relativity has been around for about a hundred years now and is very unintuitive, but despite that, it has managed to overcome all tests so far,”</em> explains Ciriaco Goddi, astronomer from the EHT. <em>“However, these tests have not been done in such strong gravitational fields.”</em></a> <p>A pressing issue in physics is that the theories of general relativity and <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Quantum_mechanics">quantum mechanics</a> seem to be fundamentally incompatible. To get to the bottom of this issue, physicists need to study the places where these theories overlap or break down. However, the conventional view is that this will not be observed at the event horizon of a supermassive black hole: quantum effects are expected to be important only near the horizon of lighter (about 10 microgram) black holes — of which we currently have no evidence for their existence. Yet some theorists argue that there will be deviations from classical general relativity close to the event horizon even for supermassive black holes, and these are potentially observable with the EHT.</p> <p><em>“If there is any deviation from Einstein’s predictions near the black hole, where gravitation is at its strongest, we would need a new theory of gravity,”</em> Goddi says, <em>“and that means that we would need to describe space and time in different terms.”</em></p> <p>General relativity predicts that the “shadow” of a black hole is circular, but other theories predict the shadow could be “squashed” along either the vertical axis (prolate) or the horizontal axis (oblate). Studying the shadow can therefore test general relativity as well as alternate theories of gravity. Plus, since the diameter of the black hole’s shadow is proportional to its mass, observing a black hole’s shadow may allow astronomers to directly estimate its mass. </p> <div style="width: 95%; margin: 40px auto"> <a href="//web.archive.org/web/20170623140317/https://www.eso.org/public/images/eventhorizon-shadows/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eventhorizon-shadows.jpg" alt="Testing general relativity with a supermassive black hole."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>This infographic shows a simulation of the outflow (bright red) from a black hole and the accretion disk around it, with simulated images of the three potential shapes of the event horizon’s shadow. Credit: ESO/N. Bartmann/A. Broderick/C.K. Chan/D. Psaltis/F. Ozel</em></div> </div> <p>ALMA astronomer Violette Impellizzeri adds: <em>We think that there is a supermassive black hole at the centre of every galaxy. But the inner workings of these black holes remain a mystery. However, we need to ask ourselves the question of why there is a supermassive black hole at the centre of every galaxy. And it’s become more and more clear that black holes play a fundamental role in the formation of galaxies, and how they evolved. So, the links between the black holes, the galaxies, and the Universe are vital to understand.”</em></p> <p>The <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Very-long-baseline_interferometry">VLBI</a> observations with the EHT and GMVA will make phenomenal new discoveries, addressing the current and pressing problems of gravitational theory.</p> <p>This is the third post of a blog series following the EHT and GMVA projects. Next time, we’ll explore how radio telescopes work. </p> <h3>Links</h3> <ul><li><a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">GMVA website</a></li> <li><a href="https://web.archive.org/web/20170623140317/https://blackholecam.org/">BlackHoleCam</a> — an EU-funded project to finally image, measure and understand astrophysical black holes</li> <li><a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Read more about ALMA</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.almaobservatory.org/en/press-room/announcements-events/900-alma-links-with-other-observatories-to-create-earth-size-telescope">Find out more about ALMA’s VLBI capabilities</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/social/">Connect with ESO on social media</a> for more exciting updates about this ambitious project.</li></ul> <div class="fb-like" data-href="https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17050201" data-layout="standard" data-action="like" data-size="small" data-show-faces="true" data-share="true"></div> <div> <br> <a href="https://web.archive.org/web/20170623140317/https://twitter.com/share" class="twitter-share-button" data-text="What’s so interesting about the event horizon? #AttemptingTheImpossible #FirstPictureOfBlackHole" data-url="https://web.archive.org/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17050201" data-show-count="true">Tweet</a><script async src="//web.archive.org/web/20170623140317js_/https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> </p> <hr> <p> </p> <div style="margin: 40px auto"><a class="anchor" name="17041101"></a><h2>2. What is a black hole?</h2> <div style="font-family: Helvetica, Arial, sans-serif; font-size: x-small; color: #4f4f4f;">11.4.2017</div></div> <p>Right now, astronomers are attempting to <a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17033001">take the first image</a> of the event horizon of the supermassive black hole at the centre of the Milky Way — but what exactly are black holes?</p> <p>Black holes are some of the most bizarre and fascinating objects in the Universe. Essentially, they’re reality-bending concentrations of matter squeezed into a very tiny space, creating an object with an immense gravitational pull. Around a black hole is a boundary called an <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Event_horizon">event horizon</a> — the surface beyond which nothing can escape the black hole’s clutches, not even light. </p> <p>Take a tour of the anatomy of a black hole with our handy infographic:</p> <div style="width: 95%; margin: 40px auto"> <a href="https://web.archive.org/web/20170623140317/https://www.eso.org/public/images/black-holes-infographic-v2/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/static/outreach/alma_first_picture_black_hole/black_holes_infographic-v2.jpg" alt="Infographic with a diagram of different parts of a black hole"></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Credit: ESO, ESA/Hubble, M. Kornmesser/N. Bartmann</em></div> </div> <p>Since no light can escape from a black hole, we can’t see them directly. But their huge gravitational influence gives away their presence. Black holes are often orbited by stars, gas and other material in tight paths that become more crowded and frantic as they’re dragged closer to the event horizon. This creates a superheated <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Accretion_disk">accretion disc</a> around the black hole, which emits vast amounts of radiation of different wavelengths.</p> <p>By observing this radiation from the activity around black holes, astronomers have determined that there are two main types: stellar mass and supermassive.</p> <p>A <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Stellar_black_hole">stellar mass black hole</a> is the corpse of a star more than about 30 times as massive as our Sun. At the end of its life, such stars violently collapse and don’t stopped collapsing until all of their constituent matter has condensed down into an unimaginably tiny space. It’s easiest to discover stellar mass black holes that are part of an <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/X-ray_binary">X-ray binary system</a>, where the black hole is guzzling down material from its companion star.</p> <div style="width: 80%; margin: 40px auto"> <a href="//web.archive.org/web/20170623140317/https://www.eso.org/public/images/eso1028a/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eso1028a.jpg" alt="Artist’s impression of the formation of a stellar black hole in a binary system."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Artist’s impression of the formation of a stellar black hole in a binary system. Credit: ESO/L. Calçada/M.Kornmesser</em></div> </div> <p>The second type is called a <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Supermassive_black_hole">supermassive black hole</a>. These gargantuan black holes are up to billions of times more massive than an average star, and how they formed is much less clear and is a matter of ongoing study. One theory proposes they formed from enormous clouds of matter that collapsed when galaxies first formed; another theory suggests that colliding stellar mass black holes can merge into one enormous object. </p> <p>Today, these supermassive monsters reside at the centres of almost every galaxy — including our own Milky Way. They exert tremendous influence on their home galaxies, especially when they gorge on gas and stars.</p> <div style="width: 80%; margin: 40px auto"> <a href="//web.archive.org/web/20170623140317/https://www.eso.org/public/images/eso1151a/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eso1151a.jpg" alt="Simulation of gas cloud after close approach to the black hole at the centre of the Milky Way."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Artist’s impression of a gas cloud after a close approach to the black hole at the centre of the Milky Way. The star orbiting the black hole are shown, along with blue lines that mark their fast, tight orbits. Credit: ESO/MPE/Marc Schartmann</em></div> </div> <p>26 000 light-years away from Earth, <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Sagittarius_A*">Sagittarius A*</a> (Sgr A* for short) is the supermassive black hole in the hot, violent centre of the Milky Way. It’s over 4 million times more massive than our Sun, over 20 million kilometres across, and is spinning at a large fraction of the speed of light. It’s shrouded from optical telescopes by dense clouds of dust and gas, so observatories that can observe different wavelengths — either longer (such as ALMA) or shorter (X-ray telescopes) — are essential to study its properties.</p> <p>Soon, through the combined power of ALMA and other millimetre-wavelength telescopes across the globe, we may become much better acquainted with the monstrous heart of our galaxy. The <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">Global mm-VLBI Array</a> is currently investigating the process of how gas, dust and other material accrete onto supermassive black holes, as well as the formation of the extremely fast gas jets that flow from them. The <a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope</a>, on the other hand, is working towards a different goal: imaging the shadow of the event horizon, the point of no return.</p> <p>This is the second post of a blog series following the EHT and GMVA projects. Stay tuned to find out more about why the event horizon of a black hole is so interesting!</p> <h3>Links</h3> <ul><li><a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">GMVA website</a></li> <li><a href="https://web.archive.org/web/20170623140317/https://blackholecam.org/">BlackHoleCam</a> — an EU-funded project to finally image, measure and understand astrophysical black holes</li> <li><a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Read more about ALMA</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.almaobservatory.org/en/press-room/announcements-events/900-alma-links-with-other-observatories-to-create-earth-size-telescope">Find out more about ALMA’s VLBI capabilities</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/social/">Connect with ESO on social media</a> for more exciting updates about this ambitious project.</li></ul> <div class="fb-like" data-href="https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17041101" data-layout="standard" data-action="like" data-size="small" data-show-faces="true" data-share="true"></div> <div> <br> <a href="https://web.archive.org/web/20170623140317/https://twitter.com/share" class="twitter-share-button" data-text="What is a black hole? #AttemptingTheImpossible #FirstPictureOfBlackHole" data-url="https://web.archive.org/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17041101" data-show-count="true">Tweet</a><script async src="//web.archive.org/web/20170623140317js_/https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> </p> <hr> <p> </p> <div style="margin: 40px auto"><a class="anchor" name="17033001"></a><h2>1. What are the Event Horizon Telescope and the Global mm-VLBI Array?</h2> <div style="font-family: Helvetica, Arial, sans-serif; font-size: x-small; color: #4f4f4f;">30.3.2017</div></div> <p>At the centre of our galaxy lurks a cosmic monster: a <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Supermassive_black_hole">supermassive black hole</a> called <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Sagittarius_A*">Sagittarius A*</a> with a mass about four million times that of the Sun. Its gravity is so intense that not even light can escape its pull, but if it wasn’t for its strong gravitational influence on the stars and gas around it, we would have no idea that it was there! Now, an ambitious new endeavour is underway to take a never-seen-before image, of the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Event_horizon">event horizon</a> of the black hole itself.</p> <p>Two international collaborations of radio telescopes have linked up to create Earth-sized virtual telescopes: the <a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope</a> (EHT) and the <a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">Global mm-VLBI Array</a> (GMVA), working at different wavelengths. The impressive line-up of telescopes, which stretch across the globe from the South Pole to Hawaii to Europe, will work together to target the supermassive black hole at the heart of the <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Supermassive_black_hole">Milky Way</a>.</p> <p>To do this, astronomers will exploit a technique known as <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/Very-long-baseline_interferometry">Very-long-baseline Interferometry</a> (VLBI), where telescopes thousands of kilometres apart can link together and act as one. This cooperative technique can achieve a far higher resolution than any single facility could obtain on its own — a resolution 2000 times that of the <a href="https://web.archive.org/web/20170623140317/https://www.spacetelescope.org/">NASA/ESA Hubble Space Telescope</a>! This super-high resolution is crucial for detecting the black hole, which — despite being about 20 times bigger than the Sun — lies a long way away, over 26 000 light-years from Earth.</p> <div style="width: 80%; margin: 40px auto"> <a href="//web.archive.org/web/20170623140317/https://www.eso.org/public/images/eht_with_title_30march/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/eht_with_title_30march.jpg" alt="Infographic of the EHT on the Earth"></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>This infographic details the locations of the participating telescopes of the Event Horizon Telescope and the Global mm-VLBI Array. Credit: ESO/O. Furtak</em></div> </div> <p>The plan to image a black hole has been in the works for years, but it’s only recently that technology has brought the ambitious endeavour within reach. Plus, a radio telescope heavyweight has just joined the team: the <a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Atacama Large Millimeter/submillimeter Array</a> (ALMA).</p> <p>Located high up on the Chajnantor plateau in Chile’s Atacama Desert, ALMA’s 66 antennas and exquisite receivers make it the largest and most sensitive component of the EHT/GMVA collaboration, increasing the overall sensitivity by a factor of 10. Despite being a state-of-the-art facility, ALMA has undergone several upgrades to take part in the collaboration. Specialist equipment has been installed, including new hard drives that are necessary to store the sheer amount of data produced by the observations, as well as an extremely accurate atomic clock, which is critical to link ALMA to the entire VLBI network. </p> <div style="width: 80%; margin: 40px auto"> <a href="//web.archive.org/web/20170623140317/https://www.eso.org/public/images/potw1252a/"><img src="//web.archive.org/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/potw1252a.jpg" alt="ALMA’s solitude"></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>ALMA’s solitude: This panoramic view of the Chajnantor Plateau shows the site of the Atacama Large Millimeter/submillimeter Array (ALMA), a place of solitude 5000 metres above sea level in the Chilean Andes. Credit: ESO/B. Tafreshi (<a href="https://web.archive.org/web/20170623140317/http://twanight.org/">twanight.org</a>)</em></div> </div> <p>The first groundbreaking observations will be made in April 2017: observations at 3 millimetre wavelengths will be made with the GMVA from 1–4 April 2017, and with the EHT at 1.3 millimetre wavelengths from 5–14 April 2017. The GMVA will investigate the properties of the accretion and outflow around the Galactic Centre, while the EHT will attempt to image, for the very first time, the shadow of the black hole’s event horizon.</p> <p>There is a long, hard road ahead to process the massive amounts of data that will be acquired during the observation periods, and results are expected to become available towards the end of 2017.</p> <p>The outcome of these observations is eagerly awaited by the astronomy community worldwide, as their scientific potential is incredibly exciting and the collaboration are pursuing some awesome goals. These could include testing Einstein’s theory of <a href="https://web.archive.org/web/20170623140317/https://en.wikipedia.org/wiki/General_relativity">general relativity</a>, which predicts a roughly circular “shadow” around the black hole. Other goals include learning about how material accretes around black holes, as well as the formation of extremely fast jets of gas that blast out from them. </p> <div style="width: 80%; margin: 40px auto"> <a href="/web/20170623140317/https://www.eso.org/public/images/shadow-evt/"><img src="/web/20170623140317im_/https://www.eso.org/public/archives/images/screen/shadow-evt.jpg" alt="Testing general relativity using the black hole shadow."></a> <div style="margin-top: 10px; margin-bottom: 10px;"><em>Simulated images of the shadow of a black hole: General relativity predicts that the shadow should be circular (middle), but a black hole could potentially also have a prolate (left) or oblate (right) shadow. Future EHT images will test this prediction. Credit: <a href="https://web.archive.org/web/20170623140317/http://www.eventhorizontelescope.org/science/general_relativity.html" target="_blank">D. Psaltis and A. Broderick</a>.</em></div> </div> <p>This is the first post of a blog series that will take you along for the astronomical ride, giving insight into how cutting-edge research is done and what risks are involved. </p> <p>In the following posts, we’ll explore questions such as: What makes black holes so interesting? How do radio telescopes see the Universe? And what do we <em>really</em> know about the supermassive monster lurking at the centre of the Milky Way?</p> <h3>Links</h3> <ul><li><a href="https://web.archive.org/web/20170623140317/http://eventhorizontelescope.org/">Event Horizon Telescope website</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/">GMVA website</a></li> <li><a href="https://web.archive.org/web/20170623140317/https://eso.org/public/teles-instr/alma/">Read more about ALMA</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.almaobservatory.org/en/press-room/announcements-events/697-alma-upgrade-to-probe-supermassive-black-hole">Read more about ALMA’s upgrades</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.almaobservatory.org/en/press-room/announcements-events/900-alma-links-with-other-observatories-to-create-earth-size-telescope">Find out more about ALMA’s VLBI capabilities</a></li> <li><a href="https://web.archive.org/web/20170623140317/http://www.eso.org/public/outreach/social/">Connect with ESO on social media</a> for more exciting updates about this ambitious project.</li></ul> <div class="fb-like" data-href="https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17033001" data-layout="standard" data-action="like" data-size="small" data-show-faces="true" data-share="true"></div> <div> <br> <a href="https://web.archive.org/web/20170623140317/https://twitter.com/share" class="twitter-share-button" data-text="What are the Event Horizon Telescope and the Global mm-VLBI Array? #AttemptingTheImpossible #FirstPictureOfBlackHole" data-url="https://web.archive.org/web/20170623140317/https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/#17033001" data-show-count="true">Tweet</a><script async src="//web.archive.org/web/20170623140317js_/https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> </p> <hr> <p> </p> </div> </div> </div> </div> </div> </div>  <div class="row footernote"> <div class="col-xs-12 col-md-4"> <a href="https://web.archive.org/web/20170623140317/mailto:information@eso.org">Send us your comments!</a> </div> <div class="col-xs-12 col-md-4"> <a href="/web/20170623140317/https://www.eso.org/public/outreach/newsletters/esonews/">Subscribe to receive news from ESO in your language</a> </div> <div class="col-xs-12 col-md-4"> <a href="https://web.archive.org/web/20170623140317/https://www.cdn77.com/">Accelerated by CDN77</a> </div> </div> <link href="/web/20170623140317cs_/https://www.eso.org/public/archives/app/css/extras.66957e81db8d.css" rel="stylesheet" type="text/css"/> <script type="text/javascript">var MEDIA_URL = "/public/archives/"</script> <script type="text/javascript" src="/web/20170623140317js_/https://www.eso.org/public/archives/app/js/main.23a8db54d0f0.js" charset="utf-8"></script> </div>  <script type="text/javascript" src="//web.archive.org/web/20170623140317js_/https://s7.addthis.com/js/300/addthis_widget.js#pubid=epod" async></script> </body> </html>