Why not take a picture of a closer black hole? Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern) What stellar content do we want to share with Twitter?Why didn't the Event Horizon Telescope team mention Sagittarius A*?Can A Black Hole Exist?Star versus Black HoleCan things move faster than light inside the event horizon of a black hole?What conditions would lead to this event around the black hole in the Pictor A galaxy?Why do “they” portray colliding black holes like that?Black Hole growthWhat will happen to the shape of a galaxy when a super massive black hole lying in its center dies(evaporates out)?Black hole, escape velocity, going up?Shouldn't we not be able to see some black holes?Is this a black hole?

Why does this iterative way of solving of equation work?

Can a non-EU citizen traveling with me come with me through the EU passport line?

How to rotate it perfectly?

What can I do if my MacBook isn’t charging but already ran out?

Jazz greats knew nothing of modes. Why are they used to improvise on standards?

Passing functions in C++

What is the order of Mitzvot in Rambam's Sefer Hamitzvot?

Need a suitable toxic chemical for a murder plot in my novel

New Order #5: where Fibonacci and Beatty meet at Wythoff

Did the new image of black hole confirm the general theory of relativity?

What do I do if technical issues prevent me from filing my return on time?

Are my PIs rude or am I just being too sensitive?

Estimate capacitor parameters

Working around an AWS network ACL rule limit

Was credit for the black hole image misattributed?

Autumning in love

How to market an anarchic city as a tourism spot to people living in civilized areas?

Can I add database to AWS RDS MySQL without creating new instance?

Single author papers against my advisor's will?

Stop battery usage [Ubuntu 18]

Using "nakedly" instead of "with nothing on"

What would be Julian Assange's expected punishment, on the current English criminal law?

What items from the Roman-age tech-level could be used to deter all creatures from entering a small area?

Is drag coefficient lowest at zero angle of attack?



Why not take a picture of a closer black hole?



Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)
What stellar content do we want to share with Twitter?Why didn't the Event Horizon Telescope team mention Sagittarius A*?Can A Black Hole Exist?Star versus Black HoleCan things move faster than light inside the event horizon of a black hole?What conditions would lead to this event around the black hole in the Pictor A galaxy?Why do “they” portray colliding black holes like that?Black Hole growthWhat will happen to the shape of a galaxy when a super massive black hole lying in its center dies(evaporates out)?Black hole, escape velocity, going up?Shouldn't we not be able to see some black holes?Is this a black hole?










55












$begingroup$


There are closer galaxies than Messier 87 for sure, even ours! It sparked my curiosity that they went with one 53 million light years away. Is there a reason for this?










share|improve this question







New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 4




    $begingroup$
    Because black holes are dangerous and the IRB wouldn't let them get too close.
    $endgroup$
    – David Richerby
    Apr 11 at 17:18










  • $begingroup$
    53 million ly is just a short trip down the road, galactically speaking.
    $endgroup$
    – PM 2Ring
    Apr 12 at 3:15










  • $begingroup$
    I'd like to ask, so as better understand your question: Why take a picture of a closer black hole?
    $endgroup$
    – Williham Totland
    2 days ago










  • $begingroup$
    Elliptical galaxy with a nice jet may have made M87 a very tempting target: duckduckgo.com/… Keep scrolling. The BH image looks to be taking over.
    $endgroup$
    – Wayfaring Stranger
    13 hours ago















55












$begingroup$


There are closer galaxies than Messier 87 for sure, even ours! It sparked my curiosity that they went with one 53 million light years away. Is there a reason for this?










share|improve this question







New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 4




    $begingroup$
    Because black holes are dangerous and the IRB wouldn't let them get too close.
    $endgroup$
    – David Richerby
    Apr 11 at 17:18










  • $begingroup$
    53 million ly is just a short trip down the road, galactically speaking.
    $endgroup$
    – PM 2Ring
    Apr 12 at 3:15










  • $begingroup$
    I'd like to ask, so as better understand your question: Why take a picture of a closer black hole?
    $endgroup$
    – Williham Totland
    2 days ago










  • $begingroup$
    Elliptical galaxy with a nice jet may have made M87 a very tempting target: duckduckgo.com/… Keep scrolling. The BH image looks to be taking over.
    $endgroup$
    – Wayfaring Stranger
    13 hours ago













55












55








55


9



$begingroup$


There are closer galaxies than Messier 87 for sure, even ours! It sparked my curiosity that they went with one 53 million light years away. Is there a reason for this?










share|improve this question







New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




There are closer galaxies than Messier 87 for sure, even ours! It sparked my curiosity that they went with one 53 million light years away. Is there a reason for this?







black-hole supermassive-black-hole event-horizon-telescope






share|improve this question







New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked Apr 10 at 23:44









MorganMorgan

378126




378126




New contributor




Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Morgan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 4




    $begingroup$
    Because black holes are dangerous and the IRB wouldn't let them get too close.
    $endgroup$
    – David Richerby
    Apr 11 at 17:18










  • $begingroup$
    53 million ly is just a short trip down the road, galactically speaking.
    $endgroup$
    – PM 2Ring
    Apr 12 at 3:15










  • $begingroup$
    I'd like to ask, so as better understand your question: Why take a picture of a closer black hole?
    $endgroup$
    – Williham Totland
    2 days ago










  • $begingroup$
    Elliptical galaxy with a nice jet may have made M87 a very tempting target: duckduckgo.com/… Keep scrolling. The BH image looks to be taking over.
    $endgroup$
    – Wayfaring Stranger
    13 hours ago












  • 4




    $begingroup$
    Because black holes are dangerous and the IRB wouldn't let them get too close.
    $endgroup$
    – David Richerby
    Apr 11 at 17:18










  • $begingroup$
    53 million ly is just a short trip down the road, galactically speaking.
    $endgroup$
    – PM 2Ring
    Apr 12 at 3:15










  • $begingroup$
    I'd like to ask, so as better understand your question: Why take a picture of a closer black hole?
    $endgroup$
    – Williham Totland
    2 days ago










  • $begingroup$
    Elliptical galaxy with a nice jet may have made M87 a very tempting target: duckduckgo.com/… Keep scrolling. The BH image looks to be taking over.
    $endgroup$
    – Wayfaring Stranger
    13 hours ago







4




4




$begingroup$
Because black holes are dangerous and the IRB wouldn't let them get too close.
$endgroup$
– David Richerby
Apr 11 at 17:18




$begingroup$
Because black holes are dangerous and the IRB wouldn't let them get too close.
$endgroup$
– David Richerby
Apr 11 at 17:18












$begingroup$
53 million ly is just a short trip down the road, galactically speaking.
$endgroup$
– PM 2Ring
Apr 12 at 3:15




$begingroup$
53 million ly is just a short trip down the road, galactically speaking.
$endgroup$
– PM 2Ring
Apr 12 at 3:15












$begingroup$
I'd like to ask, so as better understand your question: Why take a picture of a closer black hole?
$endgroup$
– Williham Totland
2 days ago




$begingroup$
I'd like to ask, so as better understand your question: Why take a picture of a closer black hole?
$endgroup$
– Williham Totland
2 days ago












$begingroup$
Elliptical galaxy with a nice jet may have made M87 a very tempting target: duckduckgo.com/… Keep scrolling. The BH image looks to be taking over.
$endgroup$
– Wayfaring Stranger
13 hours ago




$begingroup$
Elliptical galaxy with a nice jet may have made M87 a very tempting target: duckduckgo.com/… Keep scrolling. The BH image looks to be taking over.
$endgroup$
– Wayfaring Stranger
13 hours ago










5 Answers
5






active

oldest

votes


















75












$begingroup$

I was surprised too when I first heard they were trying to image M87's black hole.



The short answer is because it's really, really big. It is 1500 times bigger (diameter) than our Sagittarius A*, and 2100 times farther away. This makes its apparent size about 70% of that of Sgr A*, which they are also attempting to image.



A cursory search of wikipedia's List of Largest black holes shows that there's no other black holes with a combination of size and closeness greater than these two.



A couple of other candidates are not too far off. Andromeda's black hole is 50x the size of ours, and at 100x the distance, it would appear half the size of Sgr A*. The Sombrero galaxy is 380 times farther way than Sgr A*, and has a black hole estimated to be 1 billion solar masses, which is 232 times Sr A*, resulting in an angular diameter about 60% of Sgr A*.



There appear to be many other considerations to which black holes were chosen, as explained in this similar question. At a guess these would include how obscured each black hole is with foreground dust/stars etc, how active (and therefore bright) the nuclei are, and their inclination w.r.t earth affecting which observatories could observe them at which times.



Edit: I've found another plausible candidate. NGC_1600 is 200 M light years away with a central black hole estimated to be 17 billion solar masses heavy. This would put it at about 40% the apparent diameter of Sgr A*.



black hole size comparison, self madeComparison of the apparent size of the largest nearby black holes



And of course obligatory XKCD to remind us how small these objects really appear.






share|improve this answer











$endgroup$








  • 39




    $begingroup$
    Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
    $endgroup$
    – Florin Andrei
    Apr 11 at 4:20






  • 4




    $begingroup$
    @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
    $endgroup$
    – pela
    Apr 11 at 9:16






  • 62




    $begingroup$
    @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
    $endgroup$
    – Konrad Rudolph
    Apr 11 at 11:16






  • 10




    $begingroup$
    @KonradRudolph I see what you did there :D
    $endgroup$
    – pela
    Apr 11 at 12:18






  • 3




    $begingroup$
    I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
    $endgroup$
    – JBentley
    2 days ago



















32












$begingroup$

There are a few criteria necessary to see a black hole with the Event Horizon Telescope. They are, in importance:



  • Active Feeding: you need a thick accretion disk with lots of matter accreting onto the black hole. M87 fits this criteria, and is a glut, consuming about 90 Earth masses a day.

  • Apparent size. Even though it is 53 million light-years away, M87 is 6.5 billion solar masses. Since the radius of the event horizon scales linearly with mass, its distance is made up for by sheer scale.





share|improve this answer











$endgroup$








  • 3




    $begingroup$
    Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
    $endgroup$
    – Chappo
    Apr 11 at 7:40






  • 2




    $begingroup$
    Mmmmm, Earth-masses. :)
    $endgroup$
    – Barmar
    Apr 11 at 18:38


















18












$begingroup$

As Ingolifs says, Sgr A* and M87* are the obvious candidates. At the press conference, Heino Falcke explained why they got a picture of M87* first:




But it would take some more time because Sagittarius A Star is 1000 times faster and smaller. Its like a toddler who is moving constantly. In comparison, M87 is much slower, like a big bear.




— The Deccan Herald






share|improve this answer








New contributor




user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$








  • 3




    $begingroup$
    That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
    $endgroup$
    – Sneftel
    2 days ago






  • 8




    $begingroup$
    @Sneftel I'm so sorry for your loss
    $endgroup$
    – Michael
    2 days ago










  • $begingroup$
    So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
    $endgroup$
    – David Tonhofer
    yesterday











  • $begingroup$
    Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
    $endgroup$
    – David Tonhofer
    yesterday


















12












$begingroup$

Another quick note - They are trying to get a photo of Sag. A*:



From Space.com




The project has been scrutinizing two black holes — the M87 behemoth, which harbors about 6.5 billion times the mass of Earth's sun, and our own Milky Way galaxy's central black hole, known as Sagittarius A*. This latter object, while still a supermassive black hole, is a runt compared to M87's beast, containing a mere 4.3 million solar masses.



Both of these objects are tough targets because of their immense distance from Earth. Sagittarius A* lies about 26,000 light-years from us, and M87's black hole is a whopping 53.5 million light-years away.



From our perspective, Sagittarius A*'s event horizon "is so small that it's the equivalent of seeing an orange on the moon or being able to read the newspaper in Los Angeles while you're sitting in New York City," Doeleman said during the SXSW event last month.



...



And in case you're wondering about Sagittarius A*: The EHT team hopes to get imagery of that supermassive black hole soon, Doeleman said today. The researchers looked at M87 first, and it's a bit easier to resolve than Sagittarius A* because it's less variable over short timescales, he explained.







share|improve this answer











$endgroup$




















    0












    $begingroup$

    The difficulty in imaging anything on the visible-light spectrum is dust. Sagitarrius A is clouded by dust clouds which can be penetrated with infrared. The M87 fulfilled the criteria of being big and relatively close while at the same time enabling light to reflect off the event horizon and not being blocked by dust clouds.






    share|improve this answer









    $endgroup$













      Your Answer








      StackExchange.ready(function()
      var channelOptions =
      tags: "".split(" "),
      id: "514"
      ;
      initTagRenderer("".split(" "), "".split(" "), channelOptions);

      StackExchange.using("externalEditor", function()
      // Have to fire editor after snippets, if snippets enabled
      if (StackExchange.settings.snippets.snippetsEnabled)
      StackExchange.using("snippets", function()
      createEditor();
      );

      else
      createEditor();

      );

      function createEditor()
      StackExchange.prepareEditor(
      heartbeatType: 'answer',
      autoActivateHeartbeat: false,
      convertImagesToLinks: false,
      noModals: true,
      showLowRepImageUploadWarning: true,
      reputationToPostImages: null,
      bindNavPrevention: true,
      postfix: "",
      imageUploader:
      brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
      contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
      allowUrls: true
      ,
      noCode: true, onDemand: true,
      discardSelector: ".discard-answer"
      ,immediatelyShowMarkdownHelp:true
      );



      );






      Morgan is a new contributor. Be nice, and check out our Code of Conduct.









      draft saved

      draft discarded


















      StackExchange.ready(
      function ()
      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fastronomy.stackexchange.com%2fquestions%2f30339%2fwhy-not-take-a-picture-of-a-closer-black-hole%23new-answer', 'question_page');

      );

      Post as a guest















      Required, but never shown

























      5 Answers
      5






      active

      oldest

      votes








      5 Answers
      5






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      75












      $begingroup$

      I was surprised too when I first heard they were trying to image M87's black hole.



      The short answer is because it's really, really big. It is 1500 times bigger (diameter) than our Sagittarius A*, and 2100 times farther away. This makes its apparent size about 70% of that of Sgr A*, which they are also attempting to image.



      A cursory search of wikipedia's List of Largest black holes shows that there's no other black holes with a combination of size and closeness greater than these two.



      A couple of other candidates are not too far off. Andromeda's black hole is 50x the size of ours, and at 100x the distance, it would appear half the size of Sgr A*. The Sombrero galaxy is 380 times farther way than Sgr A*, and has a black hole estimated to be 1 billion solar masses, which is 232 times Sr A*, resulting in an angular diameter about 60% of Sgr A*.



      There appear to be many other considerations to which black holes were chosen, as explained in this similar question. At a guess these would include how obscured each black hole is with foreground dust/stars etc, how active (and therefore bright) the nuclei are, and their inclination w.r.t earth affecting which observatories could observe them at which times.



      Edit: I've found another plausible candidate. NGC_1600 is 200 M light years away with a central black hole estimated to be 17 billion solar masses heavy. This would put it at about 40% the apparent diameter of Sgr A*.



      black hole size comparison, self madeComparison of the apparent size of the largest nearby black holes



      And of course obligatory XKCD to remind us how small these objects really appear.






      share|improve this answer











      $endgroup$








      • 39




        $begingroup$
        Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
        $endgroup$
        – Florin Andrei
        Apr 11 at 4:20






      • 4




        $begingroup$
        @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
        $endgroup$
        – pela
        Apr 11 at 9:16






      • 62




        $begingroup$
        @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
        $endgroup$
        – Konrad Rudolph
        Apr 11 at 11:16






      • 10




        $begingroup$
        @KonradRudolph I see what you did there :D
        $endgroup$
        – pela
        Apr 11 at 12:18






      • 3




        $begingroup$
        I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
        $endgroup$
        – JBentley
        2 days ago
















      75












      $begingroup$

      I was surprised too when I first heard they were trying to image M87's black hole.



      The short answer is because it's really, really big. It is 1500 times bigger (diameter) than our Sagittarius A*, and 2100 times farther away. This makes its apparent size about 70% of that of Sgr A*, which they are also attempting to image.



      A cursory search of wikipedia's List of Largest black holes shows that there's no other black holes with a combination of size and closeness greater than these two.



      A couple of other candidates are not too far off. Andromeda's black hole is 50x the size of ours, and at 100x the distance, it would appear half the size of Sgr A*. The Sombrero galaxy is 380 times farther way than Sgr A*, and has a black hole estimated to be 1 billion solar masses, which is 232 times Sr A*, resulting in an angular diameter about 60% of Sgr A*.



      There appear to be many other considerations to which black holes were chosen, as explained in this similar question. At a guess these would include how obscured each black hole is with foreground dust/stars etc, how active (and therefore bright) the nuclei are, and their inclination w.r.t earth affecting which observatories could observe them at which times.



      Edit: I've found another plausible candidate. NGC_1600 is 200 M light years away with a central black hole estimated to be 17 billion solar masses heavy. This would put it at about 40% the apparent diameter of Sgr A*.



      black hole size comparison, self madeComparison of the apparent size of the largest nearby black holes



      And of course obligatory XKCD to remind us how small these objects really appear.






      share|improve this answer











      $endgroup$








      • 39




        $begingroup$
        Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
        $endgroup$
        – Florin Andrei
        Apr 11 at 4:20






      • 4




        $begingroup$
        @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
        $endgroup$
        – pela
        Apr 11 at 9:16






      • 62




        $begingroup$
        @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
        $endgroup$
        – Konrad Rudolph
        Apr 11 at 11:16






      • 10




        $begingroup$
        @KonradRudolph I see what you did there :D
        $endgroup$
        – pela
        Apr 11 at 12:18






      • 3




        $begingroup$
        I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
        $endgroup$
        – JBentley
        2 days ago














      75












      75








      75





      $begingroup$

      I was surprised too when I first heard they were trying to image M87's black hole.



      The short answer is because it's really, really big. It is 1500 times bigger (diameter) than our Sagittarius A*, and 2100 times farther away. This makes its apparent size about 70% of that of Sgr A*, which they are also attempting to image.



      A cursory search of wikipedia's List of Largest black holes shows that there's no other black holes with a combination of size and closeness greater than these two.



      A couple of other candidates are not too far off. Andromeda's black hole is 50x the size of ours, and at 100x the distance, it would appear half the size of Sgr A*. The Sombrero galaxy is 380 times farther way than Sgr A*, and has a black hole estimated to be 1 billion solar masses, which is 232 times Sr A*, resulting in an angular diameter about 60% of Sgr A*.



      There appear to be many other considerations to which black holes were chosen, as explained in this similar question. At a guess these would include how obscured each black hole is with foreground dust/stars etc, how active (and therefore bright) the nuclei are, and their inclination w.r.t earth affecting which observatories could observe them at which times.



      Edit: I've found another plausible candidate. NGC_1600 is 200 M light years away with a central black hole estimated to be 17 billion solar masses heavy. This would put it at about 40% the apparent diameter of Sgr A*.



      black hole size comparison, self madeComparison of the apparent size of the largest nearby black holes



      And of course obligatory XKCD to remind us how small these objects really appear.






      share|improve this answer











      $endgroup$



      I was surprised too when I first heard they were trying to image M87's black hole.



      The short answer is because it's really, really big. It is 1500 times bigger (diameter) than our Sagittarius A*, and 2100 times farther away. This makes its apparent size about 70% of that of Sgr A*, which they are also attempting to image.



      A cursory search of wikipedia's List of Largest black holes shows that there's no other black holes with a combination of size and closeness greater than these two.



      A couple of other candidates are not too far off. Andromeda's black hole is 50x the size of ours, and at 100x the distance, it would appear half the size of Sgr A*. The Sombrero galaxy is 380 times farther way than Sgr A*, and has a black hole estimated to be 1 billion solar masses, which is 232 times Sr A*, resulting in an angular diameter about 60% of Sgr A*.



      There appear to be many other considerations to which black holes were chosen, as explained in this similar question. At a guess these would include how obscured each black hole is with foreground dust/stars etc, how active (and therefore bright) the nuclei are, and their inclination w.r.t earth affecting which observatories could observe them at which times.



      Edit: I've found another plausible candidate. NGC_1600 is 200 M light years away with a central black hole estimated to be 17 billion solar masses heavy. This would put it at about 40% the apparent diameter of Sgr A*.



      black hole size comparison, self madeComparison of the apparent size of the largest nearby black holes



      And of course obligatory XKCD to remind us how small these objects really appear.







      share|improve this answer














      share|improve this answer



      share|improve this answer








      edited 2 days ago

























      answered Apr 11 at 0:23









      IngolifsIngolifs

      2,0461921




      2,0461921







      • 39




        $begingroup$
        Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
        $endgroup$
        – Florin Andrei
        Apr 11 at 4:20






      • 4




        $begingroup$
        @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
        $endgroup$
        – pela
        Apr 11 at 9:16






      • 62




        $begingroup$
        @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
        $endgroup$
        – Konrad Rudolph
        Apr 11 at 11:16






      • 10




        $begingroup$
        @KonradRudolph I see what you did there :D
        $endgroup$
        – pela
        Apr 11 at 12:18






      • 3




        $begingroup$
        I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
        $endgroup$
        – JBentley
        2 days ago













      • 39




        $begingroup$
        Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
        $endgroup$
        – Florin Andrei
        Apr 11 at 4:20






      • 4




        $begingroup$
        @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
        $endgroup$
        – pela
        Apr 11 at 9:16






      • 62




        $begingroup$
        @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
        $endgroup$
        – Konrad Rudolph
        Apr 11 at 11:16






      • 10




        $begingroup$
        @KonradRudolph I see what you did there :D
        $endgroup$
        – pela
        Apr 11 at 12:18






      • 3




        $begingroup$
        I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
        $endgroup$
        – JBentley
        2 days ago








      39




      39




      $begingroup$
      Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
      $endgroup$
      – Florin Andrei
      Apr 11 at 4:20




      $begingroup$
      Don't forget to say space is kind of dusty in the direction of Sgr A*. It's quite a bit clearer in the direction of M87.
      $endgroup$
      – Florin Andrei
      Apr 11 at 4:20




      4




      4




      $begingroup$
      @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
      $endgroup$
      – pela
      Apr 11 at 9:16




      $begingroup$
      @FlorinAndrei Actually that doesn't really matter much, since the observations are made in radio where there's barely any extinction.
      $endgroup$
      – pela
      Apr 11 at 9:16




      62




      62




      $begingroup$
      @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
      $endgroup$
      – Konrad Rudolph
      Apr 11 at 11:16




      $begingroup$
      @FlorinAndrei It may be dusty in the direction of Sgr A* but it’s messier in the direction of M87.
      $endgroup$
      – Konrad Rudolph
      Apr 11 at 11:16




      10




      10




      $begingroup$
      @KonradRudolph I see what you did there :D
      $endgroup$
      – pela
      Apr 11 at 12:18




      $begingroup$
      @KonradRudolph I see what you did there :D
      $endgroup$
      – pela
      Apr 11 at 12:18




      3




      3




      $begingroup$
      I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
      $endgroup$
      – JBentley
      2 days ago





      $begingroup$
      I'm not sure this answer really fully answers the question. In the "short answer" paragraph, it states that M87's apparent size is 70% that of Sgr A*. That, by itself, would appear to make it a worse candidate than Sgr A*. The question wants to know why a closer black hole wasn't chosen. Sgr A* is closer - why not choose it (and indeed the question even wants to know why not "even ours")? The answer would be improved by elaborating on the other factors that make M87 a better candidate than Sgr A*
      $endgroup$
      – JBentley
      2 days ago












      32












      $begingroup$

      There are a few criteria necessary to see a black hole with the Event Horizon Telescope. They are, in importance:



      • Active Feeding: you need a thick accretion disk with lots of matter accreting onto the black hole. M87 fits this criteria, and is a glut, consuming about 90 Earth masses a day.

      • Apparent size. Even though it is 53 million light-years away, M87 is 6.5 billion solar masses. Since the radius of the event horizon scales linearly with mass, its distance is made up for by sheer scale.





      share|improve this answer











      $endgroup$








      • 3




        $begingroup$
        Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
        $endgroup$
        – Chappo
        Apr 11 at 7:40






      • 2




        $begingroup$
        Mmmmm, Earth-masses. :)
        $endgroup$
        – Barmar
        Apr 11 at 18:38















      32












      $begingroup$

      There are a few criteria necessary to see a black hole with the Event Horizon Telescope. They are, in importance:



      • Active Feeding: you need a thick accretion disk with lots of matter accreting onto the black hole. M87 fits this criteria, and is a glut, consuming about 90 Earth masses a day.

      • Apparent size. Even though it is 53 million light-years away, M87 is 6.5 billion solar masses. Since the radius of the event horizon scales linearly with mass, its distance is made up for by sheer scale.





      share|improve this answer











      $endgroup$








      • 3




        $begingroup$
        Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
        $endgroup$
        – Chappo
        Apr 11 at 7:40






      • 2




        $begingroup$
        Mmmmm, Earth-masses. :)
        $endgroup$
        – Barmar
        Apr 11 at 18:38













      32












      32








      32





      $begingroup$

      There are a few criteria necessary to see a black hole with the Event Horizon Telescope. They are, in importance:



      • Active Feeding: you need a thick accretion disk with lots of matter accreting onto the black hole. M87 fits this criteria, and is a glut, consuming about 90 Earth masses a day.

      • Apparent size. Even though it is 53 million light-years away, M87 is 6.5 billion solar masses. Since the radius of the event horizon scales linearly with mass, its distance is made up for by sheer scale.





      share|improve this answer











      $endgroup$



      There are a few criteria necessary to see a black hole with the Event Horizon Telescope. They are, in importance:



      • Active Feeding: you need a thick accretion disk with lots of matter accreting onto the black hole. M87 fits this criteria, and is a glut, consuming about 90 Earth masses a day.

      • Apparent size. Even though it is 53 million light-years away, M87 is 6.5 billion solar masses. Since the radius of the event horizon scales linearly with mass, its distance is made up for by sheer scale.






      share|improve this answer














      share|improve this answer



      share|improve this answer








      edited Apr 11 at 5:27









      Cendolt

      677




      677










      answered Apr 11 at 0:55









      cmscms

      52615




      52615







      • 3




        $begingroup$
        Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
        $endgroup$
        – Chappo
        Apr 11 at 7:40






      • 2




        $begingroup$
        Mmmmm, Earth-masses. :)
        $endgroup$
        – Barmar
        Apr 11 at 18:38












      • 3




        $begingroup$
        Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
        $endgroup$
        – Chappo
        Apr 11 at 7:40






      • 2




        $begingroup$
        Mmmmm, Earth-masses. :)
        $endgroup$
        – Barmar
        Apr 11 at 18:38







      3




      3




      $begingroup$
      Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
      $endgroup$
      – Chappo
      Apr 11 at 7:40




      $begingroup$
      Calculates quickly... the M87 BH consumes one Earth mass every 16 MINUTES!
      $endgroup$
      – Chappo
      Apr 11 at 7:40




      2




      2




      $begingroup$
      Mmmmm, Earth-masses. :)
      $endgroup$
      – Barmar
      Apr 11 at 18:38




      $begingroup$
      Mmmmm, Earth-masses. :)
      $endgroup$
      – Barmar
      Apr 11 at 18:38











      18












      $begingroup$

      As Ingolifs says, Sgr A* and M87* are the obvious candidates. At the press conference, Heino Falcke explained why they got a picture of M87* first:




      But it would take some more time because Sagittarius A Star is 1000 times faster and smaller. Its like a toddler who is moving constantly. In comparison, M87 is much slower, like a big bear.




      — The Deccan Herald






      share|improve this answer








      New contributor




      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      $endgroup$








      • 3




        $begingroup$
        That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
        $endgroup$
        – Sneftel
        2 days ago






      • 8




        $begingroup$
        @Sneftel I'm so sorry for your loss
        $endgroup$
        – Michael
        2 days ago










      • $begingroup$
        So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
        $endgroup$
        – David Tonhofer
        yesterday











      • $begingroup$
        Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
        $endgroup$
        – David Tonhofer
        yesterday















      18












      $begingroup$

      As Ingolifs says, Sgr A* and M87* are the obvious candidates. At the press conference, Heino Falcke explained why they got a picture of M87* first:




      But it would take some more time because Sagittarius A Star is 1000 times faster and smaller. Its like a toddler who is moving constantly. In comparison, M87 is much slower, like a big bear.




      — The Deccan Herald






      share|improve this answer








      New contributor




      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      $endgroup$








      • 3




        $begingroup$
        That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
        $endgroup$
        – Sneftel
        2 days ago






      • 8




        $begingroup$
        @Sneftel I'm so sorry for your loss
        $endgroup$
        – Michael
        2 days ago










      • $begingroup$
        So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
        $endgroup$
        – David Tonhofer
        yesterday











      • $begingroup$
        Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
        $endgroup$
        – David Tonhofer
        yesterday













      18












      18








      18





      $begingroup$

      As Ingolifs says, Sgr A* and M87* are the obvious candidates. At the press conference, Heino Falcke explained why they got a picture of M87* first:




      But it would take some more time because Sagittarius A Star is 1000 times faster and smaller. Its like a toddler who is moving constantly. In comparison, M87 is much slower, like a big bear.




      — The Deccan Herald






      share|improve this answer








      New contributor




      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      $endgroup$



      As Ingolifs says, Sgr A* and M87* are the obvious candidates. At the press conference, Heino Falcke explained why they got a picture of M87* first:




      But it would take some more time because Sagittarius A Star is 1000 times faster and smaller. Its like a toddler who is moving constantly. In comparison, M87 is much slower, like a big bear.




      — The Deccan Herald







      share|improve this answer








      New contributor




      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this answer



      share|improve this answer






      New contributor




      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      answered Apr 11 at 9:10









      user24582user24582

      2812




      2812




      New contributor




      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.





      New contributor





      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      user24582 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      • 3




        $begingroup$
        That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
        $endgroup$
        – Sneftel
        2 days ago






      • 8




        $begingroup$
        @Sneftel I'm so sorry for your loss
        $endgroup$
        – Michael
        2 days ago










      • $begingroup$
        So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
        $endgroup$
        – David Tonhofer
        yesterday











      • $begingroup$
        Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
        $endgroup$
        – David Tonhofer
        yesterday












      • 3




        $begingroup$
        That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
        $endgroup$
        – Sneftel
        2 days ago






      • 8




        $begingroup$
        @Sneftel I'm so sorry for your loss
        $endgroup$
        – Michael
        2 days ago










      • $begingroup$
        So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
        $endgroup$
        – David Tonhofer
        yesterday











      • $begingroup$
        Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
        $endgroup$
        – David Tonhofer
        yesterday







      3




      3




      $begingroup$
      That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
      $endgroup$
      – Sneftel
      2 days ago




      $begingroup$
      That analogy doesn't really work. I can reliably confirm that a toddler runs slower than a bear.
      $endgroup$
      – Sneftel
      2 days ago




      8




      8




      $begingroup$
      @Sneftel I'm so sorry for your loss
      $endgroup$
      – Michael
      2 days ago




      $begingroup$
      @Sneftel I'm so sorry for your loss
      $endgroup$
      – Michael
      2 days ago












      $begingroup$
      So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
      $endgroup$
      – David Tonhofer
      yesterday





      $begingroup$
      So M87* is like Mord, the flying murderous Bear from one of Jeff Vandermeer's novels? It's a good name for a Black Hole.
      $endgroup$
      – David Tonhofer
      yesterday













      $begingroup$
      Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
      $endgroup$
      – David Tonhofer
      yesterday




      $begingroup$
      Ah, it's got an official name now: "Powehi", which apparently is Hawaiian for "embellished dark source of unending creation." which sounds really inappropriate for a maximum intensity shredder or a dark trouser leg from the universe's future. Greg Egan once proposed "Goudal-e-Markaz" ("Pit at Center") for Sgr A*, which sounds really good.
      $endgroup$
      – David Tonhofer
      yesterday











      12












      $begingroup$

      Another quick note - They are trying to get a photo of Sag. A*:



      From Space.com




      The project has been scrutinizing two black holes — the M87 behemoth, which harbors about 6.5 billion times the mass of Earth's sun, and our own Milky Way galaxy's central black hole, known as Sagittarius A*. This latter object, while still a supermassive black hole, is a runt compared to M87's beast, containing a mere 4.3 million solar masses.



      Both of these objects are tough targets because of their immense distance from Earth. Sagittarius A* lies about 26,000 light-years from us, and M87's black hole is a whopping 53.5 million light-years away.



      From our perspective, Sagittarius A*'s event horizon "is so small that it's the equivalent of seeing an orange on the moon or being able to read the newspaper in Los Angeles while you're sitting in New York City," Doeleman said during the SXSW event last month.



      ...



      And in case you're wondering about Sagittarius A*: The EHT team hopes to get imagery of that supermassive black hole soon, Doeleman said today. The researchers looked at M87 first, and it's a bit easier to resolve than Sagittarius A* because it's less variable over short timescales, he explained.







      share|improve this answer











      $endgroup$

















        12












        $begingroup$

        Another quick note - They are trying to get a photo of Sag. A*:



        From Space.com




        The project has been scrutinizing two black holes — the M87 behemoth, which harbors about 6.5 billion times the mass of Earth's sun, and our own Milky Way galaxy's central black hole, known as Sagittarius A*. This latter object, while still a supermassive black hole, is a runt compared to M87's beast, containing a mere 4.3 million solar masses.



        Both of these objects are tough targets because of their immense distance from Earth. Sagittarius A* lies about 26,000 light-years from us, and M87's black hole is a whopping 53.5 million light-years away.



        From our perspective, Sagittarius A*'s event horizon "is so small that it's the equivalent of seeing an orange on the moon or being able to read the newspaper in Los Angeles while you're sitting in New York City," Doeleman said during the SXSW event last month.



        ...



        And in case you're wondering about Sagittarius A*: The EHT team hopes to get imagery of that supermassive black hole soon, Doeleman said today. The researchers looked at M87 first, and it's a bit easier to resolve than Sagittarius A* because it's less variable over short timescales, he explained.







        share|improve this answer











        $endgroup$















          12












          12








          12





          $begingroup$

          Another quick note - They are trying to get a photo of Sag. A*:



          From Space.com




          The project has been scrutinizing two black holes — the M87 behemoth, which harbors about 6.5 billion times the mass of Earth's sun, and our own Milky Way galaxy's central black hole, known as Sagittarius A*. This latter object, while still a supermassive black hole, is a runt compared to M87's beast, containing a mere 4.3 million solar masses.



          Both of these objects are tough targets because of their immense distance from Earth. Sagittarius A* lies about 26,000 light-years from us, and M87's black hole is a whopping 53.5 million light-years away.



          From our perspective, Sagittarius A*'s event horizon "is so small that it's the equivalent of seeing an orange on the moon or being able to read the newspaper in Los Angeles while you're sitting in New York City," Doeleman said during the SXSW event last month.



          ...



          And in case you're wondering about Sagittarius A*: The EHT team hopes to get imagery of that supermassive black hole soon, Doeleman said today. The researchers looked at M87 first, and it's a bit easier to resolve than Sagittarius A* because it's less variable over short timescales, he explained.







          share|improve this answer











          $endgroup$



          Another quick note - They are trying to get a photo of Sag. A*:



          From Space.com




          The project has been scrutinizing two black holes — the M87 behemoth, which harbors about 6.5 billion times the mass of Earth's sun, and our own Milky Way galaxy's central black hole, known as Sagittarius A*. This latter object, while still a supermassive black hole, is a runt compared to M87's beast, containing a mere 4.3 million solar masses.



          Both of these objects are tough targets because of their immense distance from Earth. Sagittarius A* lies about 26,000 light-years from us, and M87's black hole is a whopping 53.5 million light-years away.



          From our perspective, Sagittarius A*'s event horizon "is so small that it's the equivalent of seeing an orange on the moon or being able to read the newspaper in Los Angeles while you're sitting in New York City," Doeleman said during the SXSW event last month.



          ...



          And in case you're wondering about Sagittarius A*: The EHT team hopes to get imagery of that supermassive black hole soon, Doeleman said today. The researchers looked at M87 first, and it's a bit easier to resolve than Sagittarius A* because it's less variable over short timescales, he explained.








          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Apr 11 at 14:55

























          answered Apr 11 at 14:48









          BruceWayneBruceWayne

          25818




          25818





















              0












              $begingroup$

              The difficulty in imaging anything on the visible-light spectrum is dust. Sagitarrius A is clouded by dust clouds which can be penetrated with infrared. The M87 fulfilled the criteria of being big and relatively close while at the same time enabling light to reflect off the event horizon and not being blocked by dust clouds.






              share|improve this answer









              $endgroup$

















                0












                $begingroup$

                The difficulty in imaging anything on the visible-light spectrum is dust. Sagitarrius A is clouded by dust clouds which can be penetrated with infrared. The M87 fulfilled the criteria of being big and relatively close while at the same time enabling light to reflect off the event horizon and not being blocked by dust clouds.






                share|improve this answer









                $endgroup$















                  0












                  0








                  0





                  $begingroup$

                  The difficulty in imaging anything on the visible-light spectrum is dust. Sagitarrius A is clouded by dust clouds which can be penetrated with infrared. The M87 fulfilled the criteria of being big and relatively close while at the same time enabling light to reflect off the event horizon and not being blocked by dust clouds.






                  share|improve this answer









                  $endgroup$



                  The difficulty in imaging anything on the visible-light spectrum is dust. Sagitarrius A is clouded by dust clouds which can be penetrated with infrared. The M87 fulfilled the criteria of being big and relatively close while at the same time enabling light to reflect off the event horizon and not being blocked by dust clouds.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered yesterday









                  Danny FDanny F

                  1234




                  1234




















                      Morgan is a new contributor. Be nice, and check out our Code of Conduct.









                      draft saved

                      draft discarded


















                      Morgan is a new contributor. Be nice, and check out our Code of Conduct.












                      Morgan is a new contributor. Be nice, and check out our Code of Conduct.











                      Morgan is a new contributor. Be nice, and check out our Code of Conduct.














                      Thanks for contributing an answer to Astronomy Stack Exchange!


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid


                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.

                      Use MathJax to format equations. MathJax reference.


                      To learn more, see our tips on writing great answers.




                      draft saved


                      draft discarded














                      StackExchange.ready(
                      function ()
                      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fastronomy.stackexchange.com%2fquestions%2f30339%2fwhy-not-take-a-picture-of-a-closer-black-hole%23new-answer', 'question_page');

                      );

                      Post as a guest















                      Required, but never shown





















































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown

































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown







                      Popular posts from this blog

                      Sum ergo cogito? 1 nng

                      三茅街道4182Guuntc Dn precexpngmageondP