<p>Black hole don't allow anything to escape, if the matter/light is inside the event horizon (boundary which describes the point of no return). The emission radiation that is referred in the question is not within the event horizon, so it can escape. This is caused by friction within matter which is swirling in to the black hole. </p>

CC BY-SA 3.0
2018-04-05T05:59:28.690Z
But what's about the radiation that it emits?
Abhishek Thawait
CC BY-SA 3.0
2018-04-05T06:02:14.147Z
technically its not black hole which emits the radiation (iam not referring to hawking radiation) , its the vicinity of blackhole which emits the radiation which results into Quasars.
Gauti
CC BY-SA 3.0
2018-04-05T06:04:06.660Z
Can you please explain about vicinity of black hole?
Abhishek Thawait
CC BY-SA 3.0
2018-04-05T05:36:47.360Z
2018-04-05T05:36:47.360Z
Gauti
<p>What you need to understand is that a black hole is a region of space defined by an <em>event horizon</em>.</p>

<p>The key point about an event horizon is that if you're inside the region it surrounds you cannot get out.  But it's only the stuff inside that is restricted in this absolute way.</p>

<p>If something is outside (even just outside) it can, in principle, happily orbit the black hole.  And in fact we know that this is possible because the <a href="https://en.wikipedia.org/wiki/Sagittarius_A*" rel="nofollow noreferrer">super massive black hole at the center of the milky way</a> is known (and was identified because of) stars that orbit it (and approach very closely).</p>

<p>Radiation emitted by material <em>near</em> a black hole can, therefore, reach us.</p>

CC BY-SA 3.0
2018-04-05T09:24:01.633Z
" (even just outside) it can, in principle, happily orbit the black hole." Not really true.
ProfRob
CC BY-SA 3.0
2018-04-06T11:34:32.337Z
What Rob said. The closest "orbits" are in the photon sphere at 1.5 times the Schwarzschild radius, but you have to be massless to orbit there, and even then your orbit is unstable.
PM 2Ring
CC BY-SA 3.0
2018-04-05T06:46:37.830Z
2018-04-05T06:46:37.830Z
StephenG - Help Ukraine
<p>We know black holes emit streams of radiation ,also recently discovered that they emit visible light when they eat any nearby matter .
        "We find that activity in the vicinity of a black hole can be observed in optical light at low luminosity for the first time," astronomer and lead researcher, Mariko Kimura from Kyoto University in Japan, told Charles Q. Choi at Space.com. 
         But it is different from what we normally hear that neither matter nor radiation can escape from black holes. 
So what's the reason for this.??</p>

CC BY-SA 3.0
2018-04-05T09:13:33.950Z
Yeah It's similar but I haven't seen that post earlier..I'm sry I could have search it on SE first.
Abhishek Thawait
<black-hole><radio-astronomy><radiation><black-body>
Strange behaviour of black holes
Abhishek Thawait
# Strange behaviour of black holes

(Asked by: username_0 on 2018-04-05)

We know black holes emit streams of radiation ,also recently discovered that they emit visible light when they eat any nearby matter .
"We find that activity in the vicinity of a black hole can be observed in optical light at low luminosity for the first time," astronomer and lead researcher, Mariko Kimura from Kyoto University in Japan, told Charles Q. Choi at Space.com. 
But it is different from what we normally hear that neither matter nor radiation can escape from black holes.
So what's the reason for this.??

**Tags:** black-hole, radio-astronomy, radiation, black-body

> **Comments:**
> **username_0**: Yeah It's similar but I haven't seen that post earlier..I'm sry I could have search it on SE first.  

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## 2 answers

### Answer by username_1 on 2018-04-05. Score: 2 | Accepted answer

Black hole don't allow anything to escape, if the matter/light is inside the event horizon (boundary which describes the point of no return). The emission radiation that is referred in the question is not within the event horizon, so it can escape. This is caused by friction within matter which is swirling in to the black hole.

> **Comments:**
> **username_0**: But what's about the radiation that it emits?  
> **username_1**: technically its not black hole which emits the radiation (iam not referring to hawking radiation) , its the vicinity of blackhole which emits the radiation which results into Quasars.  
> **username_0**: Can you please explain about vicinity of black hole?  

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### Answer by username_2 on 2018-04-05. Score: 2

What you need to understand is that a black hole is a region of space defined by an *event horizon*.

The key point about an event horizon is that if you're inside the region it surrounds you cannot get out. But it's only the stuff inside that is restricted in this absolute way.

If something is outside (even just outside) it can, in principle, happily orbit the black hole. And in fact we know that this is possible because the [super massive black hole at the center of the milky way](https://en.wikipedia.org/wiki/Sagittarius_A*) is known (and was identified because of) stars that orbit it (and approach very closely).

Radiation emitted by material *near* a black hole can, therefore, reach us.

> **Comments:**
> **username_3**: " (even just outside) it can, in principle, happily orbit the black hole." Not really true.  
> **username_4**: What Rob said. The closest "orbits" are in the photon sphere at 1.5 times the Schwarzschild radius, but you have to be massless to orbit there, and even then your orbit is unstable.  

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