🕷️ Crawler Inspector

URL Lookup

Direct Parameter Lookup

Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 70 (from laksa022)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa070.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture","crawl_time":1776101707,"first_indexed_time":1554905002,"http_code":200,"src_unparsed":"org,sciencenews!www,\/article\/event-horizon-telescope-black-hole-picture s443","src_root_hash":"11628747150769427070","history_drop_reason":null,"meta_title":"How scientists took the first picture of a black hole","meta_descriptions":["Here’s how scientists connected eight observatories across the world to create one Earth-sized telescope in order to create an image of a black hole."],"attrs_boilerpipe_text":"Black holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible.\nLuckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the\nfirst image of a supermassive black hole, the one inside the galaxy M87\n.\n“There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.”\nCreating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own.\nGetting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope.\nNRAO\/AUI\/NSF\nGetting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope.\nNRAO\/AUI\/NSF\nPutting the ‘solution’ in resolution\nWeighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A* or Sgr A* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky.\nOnly a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish.\nEven for radio astronomers, who are\nno strangers to building big dishes\n(\nSN Online: 9\/29\/17\n), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.”\nInstead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain.\nTelescopes, assemble!\nThe EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got\nthe first good look\nat the base of one of the plasma jets spewing from the center of M87’s black hole (\nSN: 11\/3\/12, p. 10\n). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself.\nOver time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter\/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories.\n“ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.”\nMore than the sum of their parts\nEHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to.\nBut planning for weather on several continents can be a logistical headache.\n“Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go\/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get.\nWhen the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A*, but M87 is in the northern sky and beyond the South Pole station’s sight.\nOn their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance.  \nHere’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location.\nM87’s supermassive black hole spits out bright jets of charged subatomic particles that extend thousands of light-years (as seen in this Hubble Space Telescope image). Researchers hope the Event Horizon Telescope’s observations will help uncover the origins of these cosmic light shows.\nHUBBLE HERITAGE TEAM (AURA\/STSCI), NASA\nFor simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like.\nThe ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates. \nPulling it all together\nIn order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years.\nThere are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times [faster than] your home internet connection,” Bower says.\nThese data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking.\nThough most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer.\nFilling in the blanks\nCombining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general.\nMaking music\nImaging a black hole with the Event Horizon Telescope is like listening to a song played on a piano with a bunch of broken keys. As seen in this video, the more working keys — or telescope pairs in the array — you have, the clearer the song. Eventually, with enough working keys (purple and blue), scientists can fill in the blanks to get the gist of the tune. In a similar way, once the EHT had enough telescope pairs collecting data in 2017, imaging software could fill in the gaps in the telescopes’ observations to produce a full image of a black hole. \nKatie Bouman\/YouTube\nThere are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense.\nBefore the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image.\n“Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image.\nBlack holes and beyond\nSo, the black hole inside M87 finally got its closeup. Now what?\nThe EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s,\nlaunch such bright plasma jets\n(\nSN Online: 3\/29\/19\n). Understanding how gas falls into and feeds black holes could also help solve the mystery of how\nsome black holes grew so quickly in the early universe\n, Loeb says (\nSN Online: 3\/16\/18\n).\nThe EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose\ncollision created gravitational waves\ndetected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO (\nSN: 3\/5\/16, p. 6\n). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for\ngravitational waves kicked up by the movement of objects like black holes\n(\nSN Online: 6\/20\/17\n).\nBesides imaging solo supermassive black holes, the Event Horizon Telescope could also search for supermassive black hole binaries, which would be targets for a space-based gravitational wave observatory called the Laser Interferometer Space Antenna.\nAurore Simonnet\/Sonoma State, MIT, Caltech, LIGO\nThe EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright.\nToo bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick.","attrs_markdown":"[Skip to content](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture#content)\n\n**Subscribe today**\n\nEvery print subscription comes with full digital access\n\n[Subscribe Now](https:\/\/www.sciencenews.org\/subscribe1?key=9MNAVBNA&utm_source=banner&utm_medium=site&utm_campaign=full_digital_access)\n\nMenu\n\n- [All Topics](https:\/\/www.sciencenews.org\/topics\/)\n  - [Health](https:\/\/www.sciencenews.org\/topic\/health-medicine)\n  - [Humans](https:\/\/www.sciencenews.org\/topic\/humans)\n    - [Anthropology](https:\/\/www.sciencenews.org\/topic\/anthropology)\n    - [Health & Medicine](https:\/\/www.sciencenews.org\/topic\/health-medicine)\n    - [Archaeology](https:\/\/www.sciencenews.org\/topic\/archaeology)\n    - [Psychology](https:\/\/www.sciencenews.org\/topic\/psychology)\n    - [View All](https:\/\/www.sciencenews.org\/topic\/humans)\n  - 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[Cosmology](https:\/\/www.sciencenews.org\/topic\/cosmology)\n      \n      ### [Exploding black holes could explain an antimatter mystery](https:\/\/www.sciencenews.org\/article\/exploding-black-holes-antimatter)\n      By [Emily Conover](https:\/\/www.sciencenews.org\/author\/emily-conover \"Posts by Emily Conover\")\n      \n      April 10, 2026\n    - [Quantum Physics](https:\/\/www.sciencenews.org\/topic\/quantum-physics)\n      \n      ### [Just 10,000 quantum bits might crack internet encryption schemes](https:\/\/www.sciencenews.org\/article\/quantum-bits-crack-internet-encryption)\n      By [Emily Conover](https:\/\/www.sciencenews.org\/author\/emily-conover \"Posts by Emily Conover\")\n      \n      April 1, 2026\n    - [Quantum Physics](https:\/\/www.sciencenews.org\/topic\/quantum-physics)\n      \n      ### [Quantum physics can confirm where someone is located](https:\/\/www.sciencenews.org\/article\/quantum-physics-location-security)\n      By [Emily Conover](https:\/\/www.sciencenews.org\/author\/emily-conover \"Posts by Emily Conover\")\n      \n      March 30, 2026\n- [Space](https:\/\/www.sciencenews.org\/topic\/space)\n  - [Space](https:\/\/www.sciencenews.org\/topic\/space)\n    - [Astronomy](https:\/\/www.sciencenews.org\/topic\/astronomy)\n    - [Planetary Science](https:\/\/www.sciencenews.org\/topic\/planetary-science)\n    - [Cosmology](https:\/\/www.sciencenews.org\/topic\/cosmology)\n  - ## Recent posts in Space\n    - [Space](https:\/\/www.sciencenews.org\/topic\/space)\n      \n      ### [Artemis II ends its historic lunar journey](https:\/\/www.sciencenews.org\/article\/artemis-ii-moon-finale)\n      By [Lisa Grossman](https:\/\/www.sciencenews.org\/author\/lisa-grossman \"Posts by Lisa Grossman\")\n      \n      April 10, 2026\n    - [Cosmology](https:\/\/www.sciencenews.org\/topic\/cosmology)\n      \n      ### [Exploding black holes could explain an antimatter mystery](https:\/\/www.sciencenews.org\/article\/exploding-black-holes-antimatter)\n      By [Emily Conover](https:\/\/www.sciencenews.org\/author\/emily-conover \"Posts by Emily Conover\")\n      \n      April 10, 2026\n    - [Space](https:\/\/www.sciencenews.org\/topic\/space)\n      \n      ### [Even before splashdown, Artemis II is delivering a scientific treasure trove](https:\/\/www.sciencenews.org\/article\/splashdown-artemis-ii-science-moon)\n      By [Lisa Grossman](https:\/\/www.sciencenews.org\/author\/lisa-grossman \"Posts by Lisa Grossman\")\n      \n      April 8, 2026\n\n[News](https:\/\/www.sciencenews.org\/article-type\/news)    [Astronomy](https:\/\/www.sciencenews.org\/topic\/astronomy)\n\n# How scientists took the first picture of a black hole\nScientists crunched data gathered by a global network of eight radio telescope observatories\n\n![ALMA telescope](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040419_mt_eht-array_feat_free.jpg?w=860)\n\n**BIGGEST TELESCOPE EVER** Telescopes across the world, including ALMA, the Atacama Large Millimeter\/submillimeter Array in Chile (pictured), joined forces to create the Event Horizon Telescope, a virtual radio dish almost as big as Earth.\n\nLuc Novovitch\/Alamy Stock Photo\n\nBy [Maria Temming](https:\/\/www.sciencenews.org\/author\/maria-temming \"Posts by Maria Temming\")\n\nApril 10, 2019 at 9:57 am - More than **2 years ago**\n\n## Share this:\n- [Share](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture)\n\n- [Share via email (Opens in new window) Email](mailto:?subject=How%20scientists%20took%20the%20first%20picture%20of%20a%20black%20hole&body=I%20saw%20this%20on%20Science%20News%3A%20https%3A%2F%2Fwww.sciencenews.org%2Farticle%2Fevent-horizon-telescope-black-hole-picture%3Futm_source%3Dinternal%26utm_medium%3Demail%26utm_campaign%3Demail_share)\n- [Share on Facebook (Opens in new window) Facebook](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture?share=facebook)\n- [Share on Reddit (Opens in new window) Reddit](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture?share=reddit)\n- [Share on X (Opens in new window) X](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture?share=twitter)\n- [Print (Opens in new window) Print](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-black-hole-picture#print?share=print)\n\nBlack holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible.\n\nLuckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the [first image of a supermassive black hole, the one inside the galaxy M87](https:\/\/www.sciencenews.org\/article\/black-hole-first-picture-event-horizon-telescope).\n\n“There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.”\n\nCreating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own.\n\n![map of EHT telescopes](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040419_mt_eht-array_inline-map_730.jpg)\n\nGetting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO\/AUI\/NSF\n\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040419_mt_eht-array_inline-map_370.jpg)\n\nGetting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO\/AUI\/NSF\n### Putting the ‘solution’ in resolution\nWeighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A\\* or Sgr A\\* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky.\n\n### Sign up for our newsletter\nWe summarize the week's scientific breakthroughs every Thursday.\n\nOnly a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish.\n\n#### More on black holes\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/041019_LG-EV-MT_EHT_feat.jpg)\n\nEVENT HORIZON TELESCOPE COLLABORATION\n\n- [The first picture of a black hole opens a new era of astrophysics](https:\/\/www.sciencenews.org\/article\/black-hole-first-picture-event-horizon-telescope)\n- [All you need to know about the history of black holes](https:\/\/www.sciencenews.org\/article\/history-black-holes-science-news)\n- [Editor’s pick: Event Horizon Telescope](https:\/\/www.sciencenews.org\/editors-picks\/event-horizon-telescope)\n\nEven for radio astronomers, who are [no strangers to building big dishes](https:\/\/www.sciencenews.org\/blog\/science-public\/new-questions-about-arecibos-future-swirl-wake-hurricane-maria) (*SN Online: 9\/29\/17*), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.”\n\nInstead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain.\n\n### Telescopes, assemble\\!\nThe EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got [the first good look](https:\/\/www.sciencenews.org\/article\/team-glimpses-black-hole%E2%80%99s-secrets) at the base of one of the plasma jets spewing from the center of M87’s black hole (*SN: 11\/3\/12, p. 10*). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself.\n\nOver time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter\/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories.\n\n“ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.”\n\n### Popular Stories\n1. [![A middle-aged woman in a pink plaid sweater blows on a single, lit candle in a cake covered with white frosting and mixed berries.](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2026\/03\/031326_JD_microdosing_main.jpg?w=330)](https:\/\/www.sciencenews.org\/article\/glp1-medications-microdose-longevity)\n   [Health & Medicine](https:\/\/www.sciencenews.org\/topic\/health-medicine)\n   \n   ### [GLP-1 microdosers are chasing longevity](https:\/\/www.sciencenews.org\/article\/glp1-medications-microdose-longevity)\n   By [Jamie Ducharme](https:\/\/www.sciencenews.org\/author\/jamie-ducharme \"Posts by Jamie Ducharme\")\n   \n   March 20, 2026\n2. 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[![The nearside of the full moon](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2026\/03\/032026_LG_crater_main_rev.jpg?w=330)](https:\/\/www.sciencenews.org\/article\/moon-new-crater-nasa-orbiter)\n   [Space](https:\/\/www.sciencenews.org\/topic\/space)\n   \n   ### [In a rare event, the moon got a massive new crater](https:\/\/www.sciencenews.org\/article\/moon-new-crater-nasa-orbiter)\n   By [Lisa Grossman](https:\/\/www.sciencenews.org\/author\/lisa-grossman \"Posts by Lisa Grossman\")\n   \n   March 23, 2026\n\n#### Dream team\nThese eight radio observatories teamed up in 2017 to work together as a global telescope, called the Event Horizon Telescope network. Their mission: to image a supermassive black hole for the first time. Data from seven were used to create a picture of the black hole inside the galaxy M87; since M87 appears in the northern sky, the South Pole observatory couldn’t see it. Here’s where the observatories are located and how many dishes they contributed to the effort.\n\n![Atacama Large Millimeter\/submillimeter Array](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow1_REV.jpg)\n\nH. Calderón\/ALMA, ESO, NRAO, NAOJ\n\n![Atacama Pathfinder Experiment](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow2_REV.jpg)\n\nB. Tafreshi\/ESO (APEX)\n\n![IRAM 30-meter telescope](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow3.jpg)\n\nNicolas Billot\/IRAM\n\n![Large Millimeter Telescope](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow4.jpg)\n\nJames Lowenthal\/Smith College, UMass Amherst (LMT)\n\n![Submillimeter Telescope](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow5_REV.jpg)\n\nDavid Harvey\/Univ. of Ariz. (SMT)\n\n![Submillimeter Array](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow7.jpg)\n\nShelbi R. Schimpf (SMA)\n\n![South Pole Telescope](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040519_mt_eht-array_slideshow8.jpg)\n\nDaniel Luong-Van\/NSF (SPT)\n### More than the sum of their parts\nEHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to.\n\nBut planning for weather on several continents can be a logistical headache.\n\n“Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go\/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get.\n\nWhen the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A\\* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A\\*, but M87 is in the northern sky and beyond the South Pole station’s sight.\n\nOn their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance.\n\nHere’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location.\n\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040319_MT_EHT_inline_2_370.jpg)\n\nM87’s supermassive black hole spits out bright jets of charged subatomic particles that extend thousands of light-years (as seen in this Hubble Space Telescope image). Researchers hope the Event Horizon Telescope’s observations will help uncover the origins of these cosmic light shows.HUBBLE HERITAGE TEAM (AURA\/STSCI), NASA\n\nFor simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like.\n\nThe ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates.\n\nSponsor Message\n\n### Pulling it all together\nIn order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years.\n\nThere are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times \\[faster than\\] your home internet connection,” Bower says.\n\nThese data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking.\n\nThough most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer.\n\n### Filling in the blanks\nCombining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general.\n\n#### Making music\nImaging a black hole with the Event Horizon Telescope is like listening to a song played on a piano with a bunch of broken keys. As seen in this video, the more working keys — or telescope pairs in the array — you have, the clearer the song. Eventually, with enough working keys (purple and blue), scientists can fill in the blanks to get the gist of the tune. In a similar way, once the EHT had enough telescope pairs collecting data in 2017, imaging software could fill in the gaps in the telescopes’ observations to produce a full image of a black hole.\n\nKatie Bouman\/YouTube\n\nThere are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense.\n\nBefore the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image.\n\n“Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image.\n\n### Black holes and beyond\nSo, the black hole inside M87 finally got its closeup. Now what?\n\nThe EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s, [launch such bright plasma jets](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-first-image-black-hole-questions?tgt=nr) (*SN Online: 3\/29\/19*). Understanding how gas falls into and feeds black holes could also help solve the mystery of how [some black holes grew so quickly in the early universe](https:\/\/www.sciencenews.org\/article\/astronomers-cant-figure-out-why-some-black-holes-got-so-big-so-fast), Loeb says (*SN Online: 3\/16\/18*).\n\nThe EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose [collision created gravitational waves](https:\/\/www.sciencenews.org\/article\/gravity-waves-black-holes-verify-einsteins-prediction) detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO (*SN: 3\/5\/16, p. 6*). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for [gravitational waves kicked up by the movement of objects like black holes](https:\/\/www.sciencenews.org\/blog\/science-ticker\/satellite-trio-will-hunt-gravitational-waves-space) (*SN Online: 6\/20\/17*).\n\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040319_MT_EHT_inline_4_730.jpg)\n\nBesides imaging solo supermassive black holes, the Event Horizon Telescope could also search for supermassive black hole binaries, which would be targets for a space-based gravitational wave observatory called the Laser Interferometer Space Antenna. Aurore Simonnet\/Sonoma State, MIT, Caltech, LIGO\n\nThe EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright.\n\nToo bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick.\n\nQuestions or comments on this article? E-mail us at [feedback@sciencenews.org](mailto:feedback@sciencenews.org) \\| [Reprints FAQ](https:\/\/www.sciencenews.org\/permission-republish)\n\nA version of this article appears in the [April 27, 2019](https:\/\/www.sciencenews.org\/sn-magazine\/april-27-2019) issue of Science News.\n\n### Citations\n[The Event Horizon Telescope](https:\/\/eventhorizontelescope.org\/)\n\n[![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2025\/05\/m_temming_new.jpg?w=80&h=80&crop=1)](https:\/\/www.sciencenews.org\/author\/maria-temming)\n\n### About [Maria Temming](https:\/\/www.sciencenews.org\/author\/maria-temming \"Posts by Maria Temming\")\n- [E-mail](mailto:mtemming@sciencenews.org)\n- [X](https:\/\/x.com\/TemmingMaria)\n\nPreviously the staff writer for physical sciences at *Science News*, Maria Temming is the assistant managing editor at *Science News Explores*. She has bachelor's degrees in physics and English, and a master's in science writing.\n\nWe are at a critical time and ***supporting climate journalism is more important than ever.*** Science News and our parent organization, the Society for Science, need your help to strengthen environmental literacy and ensure that our response to climate change is informed by science.\n\nPlease  [subscribe to *Science News* and **add \\$16**](https:\/\/www.sciencenews.org\/subscribe1-print-digital?key=9MENDTEST&utm_source=end-of-article&utm_medium=site&utm_campaign=non-sub-control) to expand science literacy and understanding.\n\n## More Stories from Science News on [Astronomy](https:\/\/www.sciencenews.org\/topic\/astronomy)\n1. 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[![An illustration of Betelgeuse and a companion star leaving a wake in its atmosphere](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2026\/01\/010625_LG_betelbuddy_feat.jpg?w=330)](https:\/\/www.sciencenews.org\/article\/betelgeuse-supergiant-star-brightness)\n   [Space](https:\/\/www.sciencenews.org\/topic\/space)\n   \n   ### [Betelgeuse’s buddy leaves a wake in the giant star’s atmosphere](https:\/\/www.sciencenews.org\/article\/betelgeuse-supergiant-star-brightness)\n   By [Lisa Grossman](https:\/\/www.sciencenews.org\/author\/lisa-grossman \"Posts by Lisa Grossman\")\n   \n   January 7, 2026\n8. [![A telescope image shows a bright, elongated galaxy with a glowing central core encircled by a warped ring of stars and gas set against a field of stars and galaxies.](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2026\/01\/010525_LG_galaxy_feat.jpg?w=330)](https:\/\/www.sciencenews.org\/article\/polar-structure-galaxies-stars-disks)\n   [Astronomy](https:\/\/www.sciencenews.org\/topic\/astronomy)\n   \n   ### [Galaxies with ‘hoop skirts’ are more common than we thought](https:\/\/www.sciencenews.org\/article\/polar-structure-galaxies-stars-disks)\n   By [Lisa Grossman](https:\/\/www.sciencenews.org\/author\/lisa-grossman \"Posts by Lisa Grossman\")\n   \n   January 7, 2026\n\n[Science News](https:\/\/www.sciencenews.org\/)\n\nScience News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. 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All rights reserved.\n\n1776 Massachusetts Ave NW, Washington, DC 20036 [202\\.785.2255](tel:202.785.2255)\n\n[Terms of Service](https:\/\/www.sciencenews.org\/terms-of-service) [Privacy Policy](https:\/\/www.sciencenews.org\/privacy-policy)\n\nPrivacy Manager\n\nClose\n\n## Log in\nSubscribers, enter your e-mail address for full access to the *Science News* archives and digital editions.\n\nNot a subscriber?  \n [Become one now](https:\/\/www.sciencenews.org\/subscription?utm_source=sciencenews&utm_medium=login&utm_campaign=sn-login&tfa_3134=sn-login).\n\nUse up and down arrow keys to explore.Use right arrow key to move into the list.Use left arrow key to move back to the parent list.Use tab key to enter the current list item.Use escape to exit the menu.Use the Shift key with the Tab key to tab back to the search input.\n\n![Logo](https:\/\/www.sciencenews.org\/wp-content\/uploads\/2025\/02\/logo.png)\n\n## Looks like your ad blocker is on.\n×\n\nWe rely on ads to keep creating quality content for you to enjoy for free.\n\nPlease support our site by disabling your ad blocker.\n\nDisable\n\nContinue without supporting us\n\n#### Choose your Ad Blocker\n- Adblock Plus\n- Adblock\n- Adguard\n- Ad Remover\n- Brave\n- Ghostery\n- uBlock Origin\n- uBlock\n- UltraBlock\n- Other\n\n1. In the extension bar, click the AdBlock Plus icon\n2. Click the large blue toggle for this website\n3. Click refresh\n\n1. In the extension bar, click the AdBlock icon\n2. Under \"Pause on this site\" click \"Always\"\n\n1. In the extension bar, click on the Adguard icon\n2. Click on the large green toggle for this website\n\n1. In the extension bar, click on the Ad Remover icon\n2. Click \"Disable on This Website\"\n\n1. In the extension bar, click on the orange lion icon\n2. Click the toggle on the top right, shifting from \"Up\" to \"Down\"\n\n1. In the extension bar, click on the Ghostery icon\n2. Click the \"Anti-Tracking\" shield so it says \"Off\"\n3. Click the \"Ad-Blocking\" stop sign so it says \"Off\"\n4. Refresh the page\n\n1. In the extension bar, click on the uBlock Origin icon\n2. Click on the big, blue power button\n3. Refresh the page\n\n1. In the extension bar, click on the uBlock icon\n2. Click on the big, blue power button\n3. Refresh the page\n\n1. In the extension bar, click on the UltraBlock icon\n2. Check the \"Disable UltraBlock\" checkbox\n\n1. Please disable your Ad Blocker\n2. Disable any DNS blocking tools such as AdGuardDNS or NextDNS\n3. Disable any privacy or tracking protection extensions such as Firefox Enhanced Tracking Protection or DuckDuckGo Privacy.\n\nIf the prompt is still appearing, please disable any tools or services you are using that block internet ads (e.g. DNS Servers, tracking protection or privacy extensions).\n\nGo Back","attrs_readable_markdown":"Black holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible.\n\nLuckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the [first image of a supermassive black hole, the one inside the galaxy M87](https:\/\/www.sciencenews.org\/article\/black-hole-first-picture-event-horizon-telescope).\n\n“There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.”\n\nCreating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own.\n\n![map of EHT telescopes](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040419_mt_eht-array_inline-map_730.jpg)\n\nGetting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO\/AUI\/NSF\n\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040419_mt_eht-array_inline-map_370.jpg)\n\nGetting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO\/AUI\/NSF\n### Putting the ‘solution’ in resolution\nWeighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A\\* or Sgr A\\* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky.\n\nOnly a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish.\n\nEven for radio astronomers, who are [no strangers to building big dishes](https:\/\/www.sciencenews.org\/blog\/science-public\/new-questions-about-arecibos-future-swirl-wake-hurricane-maria) (*SN Online: 9\/29\/17*), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.”\n\nInstead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain.\n\n### Telescopes, assemble\\!\nThe EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got [the first good look](https:\/\/www.sciencenews.org\/article\/team-glimpses-black-hole%E2%80%99s-secrets) at the base of one of the plasma jets spewing from the center of M87’s black hole (*SN: 11\/3\/12, p. 10*). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself.\n\nOver time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter\/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories.\n\n“ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.”\n\n### More than the sum of their parts\nEHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to.\n\nBut planning for weather on several continents can be a logistical headache.\n\n“Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go\/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get.\n\nWhen the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A\\* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A\\*, but M87 is in the northern sky and beyond the South Pole station’s sight.\n\nOn their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance.\n\nHere’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location.\n\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040319_MT_EHT_inline_2_370.jpg)\n\nM87’s supermassive black hole spits out bright jets of charged subatomic particles that extend thousands of light-years (as seen in this Hubble Space Telescope image). Researchers hope the Event Horizon Telescope’s observations will help uncover the origins of these cosmic light shows.HUBBLE HERITAGE TEAM (AURA\/STSCI), NASA\n\nFor simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like.\n\nThe ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates.\n\n### Pulling it all together\nIn order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years.\n\nThere are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times \\[faster than\\] your home internet connection,” Bower says.\n\nThese data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking.\n\nThough most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer.\n\n### Filling in the blanks\nCombining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general.\n\n#### Making music\nImaging a black hole with the Event Horizon Telescope is like listening to a song played on a piano with a bunch of broken keys. As seen in this video, the more working keys — or telescope pairs in the array — you have, the clearer the song. Eventually, with enough working keys (purple and blue), scientists can fill in the blanks to get the gist of the tune. In a similar way, once the EHT had enough telescope pairs collecting data in 2017, imaging software could fill in the gaps in the telescopes’ observations to produce a full image of a black hole.\n\nKatie Bouman\/YouTube\n\nThere are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense.\n\nBefore the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image.\n\n“Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image.\n\n### Black holes and beyond\nSo, the black hole inside M87 finally got its closeup. Now what?\n\nThe EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s, [launch such bright plasma jets](https:\/\/www.sciencenews.org\/article\/event-horizon-telescope-first-image-black-hole-questions?tgt=nr) (*SN Online: 3\/29\/19*). Understanding how gas falls into and feeds black holes could also help solve the mystery of how [some black holes grew so quickly in the early universe](https:\/\/www.sciencenews.org\/article\/astronomers-cant-figure-out-why-some-black-holes-got-so-big-so-fast), Loeb says (*SN Online: 3\/16\/18*).\n\nThe EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose [collision created gravitational waves](https:\/\/www.sciencenews.org\/article\/gravity-waves-black-holes-verify-einsteins-prediction) detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO (*SN: 3\/5\/16, p. 6*). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for [gravitational waves kicked up by the movement of objects like black holes](https:\/\/www.sciencenews.org\/blog\/science-ticker\/satellite-trio-will-hunt-gravitational-waves-space) (*SN Online: 6\/20\/17*).\n\n![](https:\/\/www.sciencenews.org\/wp-content\/uploads\/sites\/2\/2019\/04\/040319_MT_EHT_inline_4_730.jpg)\n\nBesides imaging solo supermassive black holes, the Event Horizon Telescope could also search for supermassive black hole binaries, which would be targets for a space-based gravitational wave observatory called the Laser Interferometer Space Antenna. Aurore Simonnet\/Sonoma State, MIT, Caltech, LIGO\n\nThe EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright.\n\nToo bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick.","meta_canonical":null}

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Boilerpipe Text	Black holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible. Luckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the first image of a supermassive black hole, the one inside the galaxy M87 . “There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.” Creating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own. Getting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO/AUI/NSF Getting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO/AUI/NSF Putting the ‘solution’ in resolution Weighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A* or Sgr A* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky. Only a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish. Even for radio astronomers, who are no strangers to building big dishes ( SN Online: 9/29/17 ), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.” Instead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain. Telescopes, assemble! The EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got the first good look at the base of one of the plasma jets spewing from the center of M87’s black hole ( SN: 11/3/12, p. 10 ). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself. Over time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories. “ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.” More than the sum of their parts EHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to. But planning for weather on several continents can be a logistical headache. “Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get. When the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A*, but M87 is in the northern sky and beyond the South Pole station’s sight. On their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance. Here’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location. M87’s supermassive black hole spits out bright jets of charged subatomic particles that extend thousands of light-years (as seen in this Hubble Space Telescope image). Researchers hope the Event Horizon Telescope’s observations will help uncover the origins of these cosmic light shows. HUBBLE HERITAGE TEAM (AURA/STSCI), NASA For simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like. The ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates. Pulling it all together In order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years. There are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times [faster than] your home internet connection,” Bower says. These data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking. Though most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer. Filling in the blanks Combining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general. Making music Imaging a black hole with the Event Horizon Telescope is like listening to a song played on a piano with a bunch of broken keys. As seen in this video, the more working keys — or telescope pairs in the array — you have, the clearer the song. Eventually, with enough working keys (purple and blue), scientists can fill in the blanks to get the gist of the tune. In a similar way, once the EHT had enough telescope pairs collecting data in 2017, imaging software could fill in the gaps in the telescopes’ observations to produce a full image of a black hole. Katie Bouman/YouTube There are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense. Before the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image. “Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image. Black holes and beyond So, the black hole inside M87 finally got its closeup. Now what? The EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s, launch such bright plasma jets ( SN Online: 3/29/19 ). Understanding how gas falls into and feeds black holes could also help solve the mystery of how some black holes grew so quickly in the early universe , Loeb says ( SN Online: 3/16/18 ). The EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose collision created gravitational waves detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO ( SN: 3/5/16, p. 6 ). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for gravitational waves kicked up by the movement of objects like black holes ( SN Online: 6/20/17 ). Besides imaging solo supermassive black holes, the Event Horizon Telescope could also search for supermassive black hole binaries, which would be targets for a space-based gravitational wave observatory called the Laser Interferometer Space Antenna. Aurore Simonnet/Sonoma State, MIT, Caltech, LIGO The EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright. Too bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick.
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Luc Novovitch/Alamy Stock Photo By [Maria Temming](https://www.sciencenews.org/author/maria-temming "Posts by Maria Temming") April 10, 2019 at 9:57 am - More than 2 years ago ## Share this: - [Share](https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture) - [Share via email (Opens in new window) Email](mailto:?subject=How%20scientists%20took%20the%20first%20picture%20of%20a%20black%20hole&body=I%20saw%20this%20on%20Science%20News%3A%20https%3A%2F%2Fwww.sciencenews.org%2Farticle%2Fevent-horizon-telescope-black-hole-picture%3Futm_source%3Dinternal%26utm_medium%3Demail%26utm_campaign%3Demail_share) - [Share on Facebook (Opens in new window) Facebook](https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture?share=facebook) - [Share on Reddit (Opens in new window) Reddit](https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture?share=reddit) - [Share on X (Opens in new window) X](https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture?share=twitter) - [Print (Opens in new window) Print](https://www.sciencenews.org/article/event-horizon-telescope-black-hole-picture#print?share=print) Black holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible. Luckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the [first image of a supermassive black hole, the one inside the galaxy M87](https://www.sciencenews.org/article/black-hole-first-picture-event-horizon-telescope). “There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.” Creating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own. ![map of EHT telescopes](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040419_mt_eht-array_inline-map_730.jpg) Getting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO/AUI/NSF ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040419_mt_eht-array_inline-map_370.jpg) Getting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO/AUI/NSF ### Putting the ‘solution’ in resolution Weighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A\* or Sgr A\* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky. ### Sign up for our newsletter We summarize the week's scientific breakthroughs every Thursday. Only a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish. #### More on black holes ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/041019_LG-EV-MT_EHT_feat.jpg) EVENT HORIZON TELESCOPE COLLABORATION - [The first picture of a black hole opens a new era of astrophysics](https://www.sciencenews.org/article/black-hole-first-picture-event-horizon-telescope) - [All you need to know about the history of black holes](https://www.sciencenews.org/article/history-black-holes-science-news) - [Editor’s pick: Event Horizon Telescope](https://www.sciencenews.org/editors-picks/event-horizon-telescope) Even for radio astronomers, who are [no strangers to building big dishes](https://www.sciencenews.org/blog/science-public/new-questions-about-arecibos-future-swirl-wake-hurricane-maria) (SN Online: 9/29/17), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.” Instead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain. ### Telescopes, assemble\! The EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got [the first good look](https://www.sciencenews.org/article/team-glimpses-black-hole%E2%80%99s-secrets) at the base of one of the plasma jets spewing from the center of M87’s black hole (SN: 11/3/12, p. 10). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself. Over time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories. “ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.” ### Popular Stories 1. [![A middle-aged woman in a pink plaid sweater blows on a single, lit candle in a cake covered with white frosting and mixed berries.](https://www.sciencenews.org/wp-content/uploads/sites/2/2026/03/031326_JD_microdosing_main.jpg?w=330)](https://www.sciencenews.org/article/glp1-medications-microdose-longevity) [Health & Medicine](https://www.sciencenews.org/topic/health-medicine) ### [GLP-1 microdosers are chasing longevity](https://www.sciencenews.org/article/glp1-medications-microdose-longevity) By [Jamie Ducharme](https://www.sciencenews.org/author/jamie-ducharme "Posts by Jamie Ducharme") March 20, 2026 2. 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[![The nearside of the full moon](https://www.sciencenews.org/wp-content/uploads/sites/2/2026/03/032026_LG_crater_main_rev.jpg?w=330)](https://www.sciencenews.org/article/moon-new-crater-nasa-orbiter) [Space](https://www.sciencenews.org/topic/space) ### [In a rare event, the moon got a massive new crater](https://www.sciencenews.org/article/moon-new-crater-nasa-orbiter) By [Lisa Grossman](https://www.sciencenews.org/author/lisa-grossman "Posts by Lisa Grossman") March 23, 2026 #### Dream team These eight radio observatories teamed up in 2017 to work together as a global telescope, called the Event Horizon Telescope network. Their mission: to image a supermassive black hole for the first time. Data from seven were used to create a picture of the black hole inside the galaxy M87; since M87 appears in the northern sky, the South Pole observatory couldn’t see it. Here’s where the observatories are located and how many dishes they contributed to the effort. ![Atacama Large Millimeter/submillimeter Array](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow1_REV.jpg) H. Calderón/ALMA, ESO, NRAO, NAOJ ![Atacama Pathfinder Experiment](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow2_REV.jpg) B. Tafreshi/ESO (APEX) ![IRAM 30-meter telescope](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow3.jpg) Nicolas Billot/IRAM ![Large Millimeter Telescope](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow4.jpg) James Lowenthal/Smith College, UMass Amherst (LMT) ![Submillimeter Telescope](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow5_REV.jpg) David Harvey/Univ. of Ariz. (SMT) ![Submillimeter Array](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow7.jpg) Shelbi R. Schimpf (SMA) ![South Pole Telescope](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040519_mt_eht-array_slideshow8.jpg) Daniel Luong-Van/NSF (SPT) ### More than the sum of their parts EHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to. But planning for weather on several continents can be a logistical headache. “Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get. When the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A\* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A\, but M87 is in the northern sky and beyond the South Pole station’s sight. On their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance. Here’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location. ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040319_MT_EHT_inline_2_370.jpg) M87’s supermassive black hole spits out bright jets of charged subatomic particles that extend thousands of light-years (as seen in this Hubble Space Telescope image). Researchers hope the Event Horizon Telescope’s observations will help uncover the origins of these cosmic light shows.HUBBLE HERITAGE TEAM (AURA/STSCI), NASA For simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like. The ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates. Sponsor Message ### Pulling it all together In order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years. There are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times \[faster than\] your home internet connection,” Bower says. These data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking. Though most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer. ### Filling in the blanks Combining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general. #### Making music Imaging a black hole with the Event Horizon Telescope is like listening to a song played on a piano with a bunch of broken keys. As seen in this video, the more working keys — or telescope pairs in the array — you have, the clearer the song. Eventually, with enough working keys (purple and blue), scientists can fill in the blanks to get the gist of the tune. In a similar way, once the EHT had enough telescope pairs collecting data in 2017, imaging software could fill in the gaps in the telescopes’ observations to produce a full image of a black hole. Katie Bouman/YouTube There are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense. Before the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image. “Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image. ### Black holes and beyond So, the black hole inside M87 finally got its closeup. Now what? The EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s, [launch such bright plasma jets](https://www.sciencenews.org/article/event-horizon-telescope-first-image-black-hole-questions?tgt=nr) (SN Online: 3/29/19). Understanding how gas falls into and feeds black holes could also help solve the mystery of how [some black holes grew so quickly in the early universe](https://www.sciencenews.org/article/astronomers-cant-figure-out-why-some-black-holes-got-so-big-so-fast), Loeb says (SN Online: 3/16/18). The EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose [collision created gravitational waves](https://www.sciencenews.org/article/gravity-waves-black-holes-verify-einsteins-prediction) detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO (SN: 3/5/16, p. 6). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for [gravitational waves kicked up by the movement of objects like black holes](https://www.sciencenews.org/blog/science-ticker/satellite-trio-will-hunt-gravitational-waves-space) (SN Online: 6/20/17). ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040319_MT_EHT_inline_4_730.jpg) Besides imaging solo supermassive black holes, the Event Horizon Telescope could also search for supermassive black hole binaries, which would be targets for a space-based gravitational wave observatory called the Laser Interferometer Space Antenna. Aurore Simonnet/Sonoma State, MIT, Caltech, LIGO The EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright. Too bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick. Questions or comments on this article? E-mail us at [feedback@sciencenews.org](mailto:feedback@sciencenews.org) \\| [Reprints FAQ](https://www.sciencenews.org/permission-republish) A version of this article appears in the [April 27, 2019](https://www.sciencenews.org/sn-magazine/april-27-2019) issue of Science News. ### Citations [The Event Horizon Telescope](https://eventhorizontelescope.org/) [![](https://www.sciencenews.org/wp-content/uploads/sites/2/2025/05/m_temming_new.jpg?w=80&h=80&crop=1)](https://www.sciencenews.org/author/maria-temming) ### About [Maria Temming](https://www.sciencenews.org/author/maria-temming "Posts by Maria Temming") - [E-mail](mailto:mtemming@sciencenews.org) - [X](https://x.com/TemmingMaria) Previously the staff writer for physical sciences at Science News, Maria Temming is the assistant managing editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing. 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Readable Markdown	Black holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible. Luckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the [first image of a supermassive black hole, the one inside the galaxy M87](https://www.sciencenews.org/article/black-hole-first-picture-event-horizon-telescope). “There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.” Creating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own. ![map of EHT telescopes](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040419_mt_eht-array_inline-map_730.jpg) Getting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO/AUI/NSF ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040419_mt_eht-array_inline-map_370.jpg) Getting the first picture of a black hole required connecting radio observatories spanning almost the entire globe in a network called the Event Horizon Telescope. NRAO/AUI/NSF ### Putting the ‘solution’ in resolution Weighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A\* or Sgr A\* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky. Only a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish. Even for radio astronomers, who are [no strangers to building big dishes](https://www.sciencenews.org/blog/science-public/new-questions-about-arecibos-future-swirl-wake-hurricane-maria) (SN Online: 9/29/17), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.” Instead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain. ### Telescopes, assemble\! The EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got [the first good look](https://www.sciencenews.org/article/team-glimpses-black-hole%E2%80%99s-secrets) at the base of one of the plasma jets spewing from the center of M87’s black hole (SN: 11/3/12, p. 10). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself. Over time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories. “ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.” ### More than the sum of their parts EHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to. But planning for weather on several continents can be a logistical headache. “Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get. When the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A\* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A\, but M87 is in the northern sky and beyond the South Pole station’s sight. On their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance. Here’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location. ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040319_MT_EHT_inline_2_370.jpg) M87’s supermassive black hole spits out bright jets of charged subatomic particles that extend thousands of light-years (as seen in this Hubble Space Telescope image). Researchers hope the Event Horizon Telescope’s observations will help uncover the origins of these cosmic light shows.HUBBLE HERITAGE TEAM (AURA/STSCI), NASA For simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like. The ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates. ### Pulling it all together In order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years. There are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times \[faster than\] your home internet connection,” Bower says. These data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking. Though most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer. ### Filling in the blanks Combining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general. #### Making music Imaging a black hole with the Event Horizon Telescope is like listening to a song played on a piano with a bunch of broken keys. As seen in this video, the more working keys — or telescope pairs in the array — you have, the clearer the song. Eventually, with enough working keys (purple and blue), scientists can fill in the blanks to get the gist of the tune. In a similar way, once the EHT had enough telescope pairs collecting data in 2017, imaging software could fill in the gaps in the telescopes’ observations to produce a full image of a black hole. Katie Bouman/YouTube There are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense. Before the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image. “Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image. ### Black holes and beyond So, the black hole inside M87 finally got its closeup. Now what? The EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s, [launch such bright plasma jets](https://www.sciencenews.org/article/event-horizon-telescope-first-image-black-hole-questions?tgt=nr) (SN Online: 3/29/19). Understanding how gas falls into and feeds black holes could also help solve the mystery of how [some black holes grew so quickly in the early universe](https://www.sciencenews.org/article/astronomers-cant-figure-out-why-some-black-holes-got-so-big-so-fast), Loeb says (SN Online: 3/16/18). The EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose [collision created gravitational waves](https://www.sciencenews.org/article/gravity-waves-black-holes-verify-einsteins-prediction) detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO (SN: 3/5/16, p. 6). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for [gravitational waves kicked up by the movement of objects like black holes](https://www.sciencenews.org/blog/science-ticker/satellite-trio-will-hunt-gravitational-waves-space) (SN Online: 6/20/17*). ![](https://www.sciencenews.org/wp-content/uploads/sites/2/2019/04/040319_MT_EHT_inline_4_730.jpg) Besides imaging solo supermassive black holes, the Event Horizon Telescope could also search for supermassive black hole binaries, which would be targets for a space-based gravitational wave observatory called the Laser Interferometer Space Antenna. Aurore Simonnet/Sonoma State, MIT, Caltech, LIGO The EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright. Too bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick.
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