Originally posted by IgnoranceIsntBlisss
If that's the case, then why can't we see that bright sun-looking center?
Short answer: it's an optical illusion.
Long answer: It's been determined that in the center of nearly every regular shaped galaxy, there is a black hole. Black holes, in turn, fire off a
huge jet of hot gasses (pulverized matter) out of the up/down poles. This produces an enormous amount of energy and light. However, a black hole is
strong enough to pull light towards itself, up to a certain distance from the black hole itself, but the light from the gas is actually emitted beyond
this radius.
So effectively, what you are seeing is the light-emission-energy of a black hole's gaseous emissions, but not the source of the emissions themselves,
because inside a certain radius, the light is sucked in, and within a narrow band, the light remains more or less static, or revolving around the
hole's radius of effect, the further out you go, the more light escapes, but at different speeds. What you end up with is a massive sorta spherical
blur of light that you can never really see the cause of, because the cause adsorbs the light that would reveal it.
Plus, light can escape far more easily than solid matter can, so you actually will have a layer of this sphere where light will still escape, but a
rock would not. So it looks like this light comes from nowhere.
However, with certain filters, over the course of months and years, scientists were able to observe stars in the center of the galaxy whirling around
this radius at incredible speeds, and I believe they even saw one simply vanish into the event horizon.
Originally posted by IgnoranceIsntBlisss
Or, how do they even
think they know it looks like that?
They think they know because of the light-shift in the doppler pattern, and the rotation of stars around the center, and the properties of the light
itself. The discovery that nearly every galaxy has a black hole at the center was quite by accident.
If I remember correctly, they observed these enormous gas jets out in space, that baffled scientists because the gasses didn't appear to come from
anything. One scientist theorized that maybe the gasses were coming from black holes, and that it could be determined by measuring the spin of stars
closest to these jets of gasses. They decided to try it on Andromeda I think, and found, to their surprise that their measurements for the light had
this really wierd shift.
In a nutshell, when they looked at Andromeda doppler shift, it's light pattern was something like this (ignore the dots, they were to get the bottom
| in place.)
__|_
..|
The light in the center top was off from the light in the center bottom. Thing is, they were expecting it to look like this:
--+--
So they ran another test some months later and found the light had shifted again:
_|__
....|
This shift, they figured, using lots of "math and stuff" could have only happened due to stars moving at incredible speed in orbit around something
so massive it's gravity could only be described as a black hole.
How lucky was that?!? They found a black hole on the first try! So they checked other galaxies. Another black hole, another, another, until out of
hundreds of galaxies checked, only a couple had no black hole, and those galaxies were irregularly shaped.
Originally posted by IgnoranceIsntBlisss
Or, can we see it but few can actually recognize it with everything else in the night sky?
You can't. Not with the naked eye. They were only able to determine our own galaxy indeed had a black hole like all the others, after years worth of
observing the position of stars closest to the center of our galaxy, and to do that, they had to use a lot of special filters and "math and
stuff".
I say "math and stuff" because while specific astrophysics is way beyond me, I know that most everything they discover is by using dimensional
math.
Originally posted by IgnoranceIsntBlisss
Furthermore, if there's a black hole in its center then wouldn't that make it inevitable that we'll end up inside it?
Not neccessarily. See, Black Holes aren't all-powerful. They have a gravitic cut-off point just like planets, stars, and so forth. Further studies in
the field have also shown that the Black Holes no longer affect galaxies past a certain distance from the center. In other words, our own system is
quite safe from being directly sucked into the black hole given all other things equal.
However, the size of a galaxy and its rate of spin is directly relative to the mass of the black hole in the center. This they have determined for
certain. Which means, when the galaxies originally formed, black holes played an enormous role in their creation, and setting them in motion.
The theory now is that, over time, the black hole sucked up everything in it's immediate area of influence that it could, and achieved a sort of
equilibrium where it no longer directly affects the galaxy past a certain point. In other words, if you were to remove the black hole suddenly, from
the center of the galaxy, the galaxy itself should, in theory, go on spinning like normal.
The reason some stars occasionally still plunge into black holes at the center is because some other gravitic force or their own orbit sent them back
into the area of influence of the black hole.
Originally posted by IgnoranceIsntBlisss
Lastly, since it's a system that our system is part of and is affected by the centers gravity, why aren't we affected by macro system events in the
way that micro things on earth are affected by the macro Sun system? Or is it?
To the best of our knowledge so far, it doesn't (see above). The black hole set us in motion and shaped our galaxy, but is now no longer neccessary
to keep us in shape or in motion.
I hope this helps, and to those members of ATS whom are astrophysicists, I hope I didn't butcher the explanation too badly.
