Why can't we see the center of the Milky Way?

We can't see outside our own galaxy.

Those renditions are all postulations built on substantial logic and reasoning in sciences.

I am told you can't see the center of the Milky Way galaxy because it is irredescent.

Originally posted by menguard

I am told you can't see the center of the Milky Way galaxy because it is irredescent.

You mean iridescent? That doesn't really make sense anyways

Guys, I have a few questions for you all, because I'm very confused with all these different names and words.

The center of our galaxy is a huge cluster of a lot of stars, and these stars are what supposedly create the big yellow light in the middle of our galaxy when viewed from an artists point of view? This cluster of stars is called Sagittarius A, right? Is Sagittarius A and just plain "Sagittarius" two different things?

The constellation Sagittarius is another word for our galaxy right? Only that you refer to the center? So Scorpius is another galaxy? I'm also confused because some people say we can't see Sagittarius A, but then how come I can find millions of photos of Saggitarius A?


And how come I've never seen Sagittarius? Do you have to be in an area with no lights whatsoever? Like in the middle of nowhere? Because I would really like to watch the sky when it looks like this:




[edit on 23-5-2007 by ZikhaN]

Yeah, Iridescent=Marked by or showing rainbow colors that appear to move and change as the angle at which they are seen changes.A lot of times things that seem far away in space are right in front of our face and rotating in all directions, it is the trippiest thing I have ever seen, depth perception is lacking out there, only our field of perception can hold things into place.See while you think you might be standing still you are picking up speed, yet things are moving right past you.They could be a hundred miles away in a minute and be right in front of you, yet you wouldn't know because the object rotates in all directions, its hard to get a lock on it.

[edit on 23-5-2007 by menguard]

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.

Can someone please answer my questions now? I haven't really had a lot of astrology in science during my school years. I only had it like once or twice a few years ago, so I've had to learn most of it by myself through curiousity.

Originally posted by Aether
We can't see outside our own galaxy.

Sure we can see the galaxy. We are far enough away from the center of it that when we look towards the direction of the center, we see a hazy "cloud" which is actually an edge-on view of the main part Milky Way (we live far out on the periphery). Here is a composite, long exposure photo of the edge-on view of our galaxy:

upload.wikimedia.org...

Here in the Northeast U.S., The Milky Way is best seen throughout July and August. On a dark, moonless July night (at about 10:00) go outside and look towards the south and about halfway up from the horizon. It's best to keep looking for several minutes to allow your eyes to get acclimated to the dark. You should see the "hazy cloud" that is actually the bulk of our galaxy.

Edit: fixed URL

[edit on 23-5-2007 by Soylent Green Is People]

Originally posted by ZikhaN
The center of our galaxy is a huge cluster of a lot of stars, and these stars are what supposedly create the big yellow light in the middle of our galaxy when viewed from an artists point of view? This cluster of stars is called Sagittarius A, right? Is Sagittarius A and just plain "Sagittarius" two different things?

Sagittarius is supposed to the one of the main clusters at the edge of one of those 2 arms (poles, whatever you call them) I believe. Perhaps Sat. B is the one on the other side. I can't help you from there.

Wow. Great Response Libra

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.

My reasoning was if this thing is constantly pulling more and more stars into that massive cluster-core center, it seemed like each new addition would add to the combined gravity there.

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.

I'm wondering where these black holes come from before accepting that as truth.

Couldn't they have formed from more simple means? For example, some gravity dense objects like 'super' stars started pulling each other together, 'early on' in all of this, and then 'gradually' one by one the cluster grew and grew and kept pulling more and more objects into their wake.

But wait... at some point the cluster 'collapses' into a "black hole'. However, it continues pulling objects into its wake and into itself. Right? Is there an actual loss of gravity in thsi sum of sums, that I'm missing? It seems to me the black hole would 'grow' with each new addition, and it's overall gravity would continue to grow as it pulled more objects near it (look at Sagittarius) further concentrating the gravity in the galaxy in question.

As an infalling object approaches the singularity, tidal forces acting on it approach infinity. All components of the object, including atoms and subatomic particles, are torn away from each other before striking the singularity. At the singularity itself, effects are unknown; a theory of quantum gravity is needed to accurately describe events near it. Regardless, as soon as an object passes within the hole's event horizon, it is lost to the outside world. An observer far from the hole simply sees the hole's mass, charge, and angular momentum change to reflect the addition of the new object's matter.
en.wikipedia.org...

Perhaps I'm being too simple here, but this doesn't seem like something to be too confident about as scientists are trying to create black holes her eon earth with particle accelerators.

Originally posted by IgnoranceIsntBlisss

Originally posted by ZikhaN
The center of our galaxy is a huge cluster of a lot of stars, and these stars are what supposedly create the big yellow light in the middle of our galaxy when viewed from an artists point of view? This cluster of stars is called Sagittarius A, right? Is Sagittarius A and just plain "Sagittarius" two different things?

Sagittarius is supposed to the one of the main clusters at the edge of one of those 2 arms (poles, whatever you call them) I believe. Perhaps Sat. B is the one on the other side. I can't help you from there.

What two arms? You mean the arms that form the spiral? Which two arms though, because there are more than two. Btw, I love your avatar. A Clockwork Orange is one of my favourite movies.

Soylent Green Is People, thanks for the information on how to view Sagittarius. I live in Sweden though, but I guess it should be the same anyways. I'm going to try to find our galaxy center by looking up in a clear moon-free sky in July. It's going to be awesome, because I've never seen space like that before. I've never even known it was possible.

By the way, do you think it matters if you're in a highly lit place? And I mean like if you're standing in a place with houses and buildings a little here and there, with street lamps and stuff. Should I try to go to a place far away from lights, so that my surroundings are as dark as possible, or does that make no difference?

[edit on 23-5-2007 by ZikhaN]

light pollution matters a great deal.
check my thread I posted today on light pollution.
or see the original link here
Declaration in Defence of the Night Sky

www.unescocan.org...


"The sky, our common and universal heritage, is an integral part of the environment perceived by humanity. Humankind has always observed the sky either to interpret it or to understand the physical laws that govern the universe. This interest in astronomy has had profound implications for science, philosophy, religion, culture and our general conception of the universe".

Originally posted by IgnoranceIsntBlisss

Originally posted by ZikhaN
The center of our galaxy is a huge cluster of a lot of stars, and these stars are what supposedly create the big yellow light in the middle of our galaxy when viewed from an artists point of view? This cluster of stars is called Sagittarius A, right? Is Sagittarius A and just plain "Sagittarius" two different things?

Sagittarius is supposed to the one of the main clusters at the edge of one of those 2 arms (poles, whatever you call them) I believe. Perhaps Sat. B is the one on the other side. I can't help you from there.

Well I've pratcically got it it all now. Sagittarius A is not a cluster of stars in the middle. Sagittarius A is the black hole at the center of our galaxy that's pulling everything into it. That's why the spiral arms are circling around, because it's being pulled by Sagittarius A's gravital force.

The cluster of stars are just floating around it, and so is the hot gas. If you're wondering why you can't see the black hole, then it's because it's got such a strong gravity force that it sucks up the light. Without light, it can't reflect the object, so our eyes can't see it.

Oh, and when something gets sucked into the supermassive black hole, it gets sent out with blast into space before it disappears forever, so the center of our galaxy sort of flickers.

[edit on 25-5-2007 by ZikhaN]