My analogy may not be right on, but I think I am close. An air traffic controller can tell you lots of things about what is in the air surrounding the airport: direction, speed, altitude, even the type of plane it is.

So if you were a celestial objects traffic controller, what would you see? I completely understand that all measurements would be relative to your position in regards to everything else you are measuring (did that even make sense). But what would the rotation of the earth look like compared to other planets in our solar system? What about the orbits of the different planets in our solar system; are they on the same plane? If not, is there a model that shows the different planes and rotations? What about other solar systems in our galaxy? Are all solar systems in our galaxy rotating around the galaxy's center (like planets around the sun)? Are all solar systems in our galaxy on the same plane? Does our galaxy rotate around something (i thought i read something that there is a stream of matter coming out the center of our galaxy)? Does it have an orbit? what does it orbit around?

Bottom line question is, "is there a model of the universe's known movements?" If so, where is this model, as i'd like to see it.

We certainly do not have enough information to model our own galaxy. It is easier to look at other galaxies and guess as to how similar or different they are from our own. However, we have a fair aproximation of our own orbital path and adjacent spiral arms. The Hipparcos data give the best information about stars close enough to us for parallax to be effective in measuring their proper motion. We have looked at the galactic center in the direction of Sagitarius with infrared and radio telescopes and determined a high probability of a black hole at the center of our galaxy. We also have good data on many dwarf galaxies orbiting our galaxy. We have barely scratched the surface. We have yet to identify all bodies in our neighborhood, asteroids, rocks, etc..

For fun look at NGC3314a,b and consider how someone living in one of those galaxies might view the other.

And, welcome.

"For fun look at NGC3314a,b and consider how someone living in one of those galaxies might view the other."

Thanks for your response! I actually had asked a similar question in an email to several astronomers. They said that the planetary orbits rotate in the same direction as the sun's spin, as the planets spin (with minor exceptions like uranus/neptune can't remember which one), as well as the galaxy's spin etc.

What is NGC3314a,b?

This from the Hubble Space telescope.
These two galaxies, by a chance alignment, happen to be one in front of another. Anytime that you see "NGC" preceeding a number it refers to a cataloged celestial object; and specifically the letters mean "New General catalog"

http://hubblesite.org/newscenter/new...000/14/image/a

Yes, indeed, serious fun. Some people get so involved that they can spend days doing so. And note that someone in NGC 3314b would have a similarly revealing view of the Milky Way backlighting at least the central part of NGC 3314a, which is about 1/3 closer to us than 3314b.

Why, you might say that some could get so carried away in that fun that they might even be inspired to choose their "handle" by it!

I've heard of even more serious cases - I know someone who spent time discussing with the NED folks how they should properly list to galaxies of different distance but almost exactly the same coordinates. The same one who has published papers on dust in NGC 3314a over more than a 20-year period with no end in sight. I tell you, I worry about some of these astronomers. Oh, yeah, same guy's mixed up in a Hubble project to look for gravitational microlensing this system, where enough events could even tell us which way the relative transverse peculiar velocity goes.

Anybody else picturing a clandestine meeting of NGC 3314 Anonymous?

You are correct and I never considered the opposite perspective. Also, I have tremendous respect for Dr. William Keel and his work with light extinction due to dust.

I am amazed at the difference in size of these two galaxies that is made so apparent by their alignment. It is so rare to have a yardstick to make the comparison.

<embarrassed blush>

We have communicated before re: redshift of the two galaxies respectively. At that time several years ago the redshift had fairly large error bars in its determination. Has that situation improved?

And your'e position and handle gave you away.

The redshifts themselves have been pretty tightly constrained for a while - I did fiber-array observations fit to symmetric rotation curves in 2D only to recover almost the exact values found by Francois Schweizer years earlier from single points looking close to the nuclei - cz=2810 km/s foreground, 4640 background. Assigning distances to these reshifts entails more uncertainty than usual, because this is the direction of the Hydra I galaxy cluster (Abell 1060). Both values lie within its 3-sigma envelope. The background one is very likely a Hydra member. However, the foreground galaxy matches the redshifts of a sparse group of bright galaxies (most notable the oversize spiral NGC 3312) all at very nearly the same redshift, with tails of H I gas seen stretching among them, which looks like a foreground group that is probably at about the redshift distance corresponding to its mean redshift. That's where the distance estimates in the Hubble Heritage release came from, and why they are unusually weaselly.

Continuing the reverse-perspective notion, there are some galaxies that we see at high redshift as multiple-image gravitationally lensed arcs which would (at some time) see the Milky Way similarly imaged. Note to self: contemplate grant proposal to compare notes with observers in those galaxies, thereby getting very strong constraints on the ratio of lensing and dynamical mass and making sure we know the relation between image geometry and amplification because that hands us part of the intervening dark-matter profile. Budget section - let's see, take the log, carry the 1, factor in preservation of information as succeeding principal investigators evolve into vacuum-hardy forms...

Excellent-- Thank You

Now, here is the really tuff question:

How many super novae did it take to produce the dust in 3314b?

There had to be a time period where those things were popping like mad!!

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wish there was a way i could understand all of this. :-) sounds intriguing.

so, there are parts of that photo that shows the 2 galaxies (one behind the other) where you cannot see light coming from the galaxy in the back? and they call this lack of light "dark matter". is that what this discussion is about?

(Sorry about the digression). The picture does show absorbing material (interstellar dust) in the foreground galaxy, where the background light makes it easier to see than usual. However, just to be confusing, this is not what is generally called dark matter! The dust shines in the infrared. The dark matter we infer from, for example, galaxy dynamics, is more properly called invisible matter, since we cannot see it emitting or absorbing light anywhere in the spectrum from gamma rays to radio waves. The dust in a galaxy like that amounts to a few tens of millions of solar masses, which is not much compared to the ten billion or so in stars and gas, and even less important compared to the 20 times or so greater still mass of dark matter that is needed to hold a typical bright spiral together gravitationally.

Tying in jlhredshift's latest question, the dust comes from several environments in which gases expand and cool quickly, whenever there are enough heavy-element atoms to produce it. We see that dust grains are formed in the debris of supernova explosions, nova outbursts, and the unstable envelopes of red supergiants stars (and maybe other places). The mix of these, and how important destruction of grains in hot environments might be, are still highly uncertain - excuse me, active topics of ongoing research.

Well, no.
Dark matter is the hypothesized material to try to explain the speeds of the light emmitting material(stars) on the outer edges of galaxies. Their speed is to high and inaccordance with Newton's law of gravity this suggests more matter than what is seen: i.e dark matter. Which goes to your question about a simulation of galatic motion.

In the picture of ngc3314a,b you can not actually see individual stars. You are seeing a combination of starlight from billions of stars plus the reflected light from the dust and gas that they are embedded in. The discussion about their recession speed and corresponding "z" value is a measurement of how fast they are moving away from us along our line of sight. And, finally, supernovae are stars at the end of their life that through nuclear fusion produces all the elements above hydrogen through iron and above and then explode. It is the product of these explosions that form the dust. Now, it is obviously more complicated than this, but, that is my short version.

Ooops!! NGC3314's explanation is better than mine. And, he posted first.