<p>I think the image you posted is not quite reallistic. On it, objects are just inverted from some radius on, while what you can expect from a real black hole seen from near enough is a combination of these:</p>

<p>a) an accretion disc
b) a companion being sucked
c) Hawking's radiation
d) X-Ray burst from the poles (really starting out of the event horizon)</p>

<p>You will not see an actual black circle, as most probably there will be a lot of matter out of the event horizon radiating.</p>

CC BY-SA 3.0
2016-04-03T19:27:29.037Z
Black holes do not necessarily have discs or companions, and certainly not companions that would be in the same image that the OP showed. Hawking radiation from a supermassive or stellar-sized black hole is utterly negligible.
ProfRob
CC BY-SA 3.0
2013-12-19T11:12:09.543Z
2013-12-19T11:12:09.543Z
Envite
<p>Since the astronomers are using radio telescopes and not optical telescopes, I'd like to point out why they are doing so - The centre of the Milky Way is a <em>very</em> dusty place. Wavelengths from the millimeter to optical get easily absorbed by all this dust, so it's very difficult to see the centre of the galaxy in the optical spectrum. But radio waves do not get absorbed, and the centre of our galaxy is a very strong source of radio waves. Therefore looking in radio will give us the clearest picture of what's happening over there.</p>

<hr>

<p>They mention in the article that they use a technique called VLBI (Very Long Baseline Interferometry) to image the blackhole.</p>

<p>The images you get from <a href="https://en.wikipedia.org/wiki/VLBI">VLBI</a> aren't images in the traditional sense, like you would get from an optical telescope. VLBI measures the phase difference of waves arriving at two different antennas (on two different continents, perhaps) and use this phase difference to infer the size of the source in the sky. Contradictorily, even though they can resolve sources of less than an arcsecond in size, it's very difficult to localize the <em>absolute</em> position in the sky to a very high degree. </p>

<p>So hopefully we will be able to resolve the event horizon of the black hole, but we will (almost definitely) not be able to see a picture like the one you posted.</p>

CC BY-SA 3.0
2014-04-04T07:46:33.663Z
Part of what Kitchi says is correct, these are radio observations using VLBI. But these data (routinely) undergo a cross-correlation analysis which, when coupled with some assumptions that aren't too unreasonable, are then turned into an 'image'. The phase/delay measurements mentioned are actually Fourier-paired with the traditional 'image space' we're used to from traditional optical telescopes. So we'll **hopefully** be able to image closer to the black hole with the BlackHoleCam (mentioned above) and the [Event Horizon Telescope](http://www.eventhorizontelescope.org/), but unfortunately the
QuantumSwordsman
CC BY-SA 3.0
2014-04-04T07:46:33.663Z
resolution these give us will still be on the order of a few [Schwarzschild radii](http://en.wikipedia.org/wiki/Schwarzschild_radius), and we therefore won't actually see a nice big resolved 'nothing' in the center of the map.
QuantumSwordsman
CC BY-SA 3.0
2013-12-28T15:53:04.067Z
2013-12-28T15:53:04.067Z
Kitchi
<p>From recent <a href="http://www.mpifr-bonn.mpg.de/announcements/2013/8" rel="nofollow noreferrer">news from the Max Planck Institute for Radio Astronomy:</a></p>

<blockquote>
  <p>The European Research Council (ERC) has awarded 14 Million Euros to a
  team of European astrophysicists to construct the first accurate image
  of a black hole. The team will test the predictions of current
  theories of gravity, including Einstein's theory of General
  Relativity.</p>
</blockquote>

<p>I've seen computer depictions of black holes in the past, are they similiar to what we can expect from this new endeavour? </p>

<p>In the next image we can see a computer model of a black hole of ten solar masses as seen from a distance of 600km with the Milky Way in the background with a horizontal camera opening angle of 90 degrees:</p>

<p><img src="https://i.sstatic.net/xF5EP.jpg" alt="A Black Hole of ten solar masses as seen from a distance of 600km with the Milky Way in the background with a horizontal camera opening angle of 90 degrees"> </p>

<p><a href="http://www.tempolimit-lichtgeschwindigkeit.de/galerie/galerie.html" rel="nofollow noreferrer">Image Source</a></p>

<black-hole><milky-way><radio-astronomy><general-relativity>
What can we expect from the first accurate image of a black hole?
Eduardo Serra
# What can we expect from the first accurate image of a black hole?

(Asked by: username_0 on 2013-12-18)

From recent [news from the Max Planck Institute for Radio Astronomy:](http://www.mpifr-bonn.mpg.de/announcements/2013/8)

> The European Research Council (ERC) has awarded 14 Million Euros to a
> team of European astrophysicists to construct the first accurate image
> of a black hole. The team will test the predictions of current
> theories of gravity, including Einstein's theory of General
> Relativity.

I've seen computer depictions of black holes in the past, are they similiar to what we can expect from this new endeavour?

In the next image we can see a computer model of a black hole of ten solar masses as seen from a distance of 600km with the Milky Way in the background with a horizontal camera opening angle of 90 degrees:

![A Black Hole of ten solar masses as seen from a distance of 600km with the Milky Way in the background with a horizontal camera opening angle of 90 degrees](https://i.sstatic.net/xF5EP.jpg)

[Image Source](http://www.tempolimit-lichtgeschwindigkeit.de/galerie/galerie.html)

**Tags:** black-hole, milky-way, radio-astronomy, general-relativity

---

## 2 answers

### Answer by username_3 on 2013-12-28. Score: 6 | Accepted answer

Since the astronomers are using radio telescopes and not optical telescopes, I'd like to point out why they are doing so - The centre of the Milky Way is a *very* dusty place. Wavelengths from the millimeter to optical get easily absorbed by all this dust, so it's very difficult to see the centre of the galaxy in the optical spectrum. But radio waves do not get absorbed, and the centre of our galaxy is a very strong source of radio waves. Therefore looking in radio will give us the clearest picture of what's happening over there.

---

They mention in the article that they use a technique called VLBI (Very Long Baseline Interferometry) to image the blackhole.

The images you get from [VLBI](https://en.wikipedia.org/wiki/VLBI) aren't images in the traditional sense, like you would get from an optical telescope. VLBI measures the phase difference of waves arriving at two different antennas (on two different continents, perhaps) and use this phase difference to infer the size of the source in the sky. Contradictorily, even though they can resolve sources of less than an arcsecond in size, it's very difficult to localize the *absolute* position in the sky to a very high degree.

So hopefully we will be able to resolve the event horizon of the black hole, but we will (almost definitely) not be able to see a picture like the one you posted.

> **Comments:**
> **username_4**: Part of what Kitchi says is correct, these are radio observations using VLBI. But these data (routinely) undergo a cross-correlation analysis which, when coupled with some assumptions that aren't too unreasonable, are then turned into an 'image'. The phase/delay measurements mentioned are actually Fourier-paired with the traditional 'image space' we're used to from traditional optical telescopes. So we'll **hopefully** be able to image closer to the black hole with the BlackHoleCam (mentioned above) and the [Event Horizon Telescope](http://www.eventhorizontelescope.org/), but unfortunately the  
> **username_4**: resolution these give us will still be on the order of a few [Schwarzschild radii](http://en.wikipedia.org/wiki/Schwarzschild_radius), and we therefore won't actually see a nice big resolved 'nothing' in the center of the map.  

---

### Answer by username_1 on 2013-12-19. Score: 3

I think the image you posted is not quite reallistic. On it, objects are just inverted from some radius on, while what you can expect from a real black hole seen from near enough is a combination of these:

a) an accretion disc
b) a companion being sucked
c) Hawking's radiation
d) X-Ray burst from the poles (really starting out of the event horizon)

You will not see an actual black circle, as most probably there will be a lot of matter out of the event horizon radiating.

> **Comments:**
> **username_2**: Black holes do not necessarily have discs or companions, and certainly not companions that would be in the same image that the OP showed. Hawking radiation from a supermassive or stellar-sized black hole is utterly negligible.  

---

