Galaxy Solar System

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Why don't galaxies for giant "solar systems"?
 

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mathman
Science Advisor
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Your question is too vague. What are you thinking of by the term "giant solar systems"?
 
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Because a 'solar system' is defined by one, two, or three closely (in terms of the overall size of the solar system) orbiting stars, with planets and other stuff orbiting them. A galaxy is typically made of many billions of stars, all orbiting their galactic center.

And, please proof-read your questions carefully - I'm assuming you meant 'form' and not 'for'.
 
turbo
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Why don't galaxies for giant "solar systems"?
We don't know your level of education, etc, so don't get too hung-up on technicalities yet. The fact is that galaxies form gravitationally-bound systems and they orbit one another in some pretty complex ways.

Interacting galaxies don't generally form nice (mostly) flat planar systems like the planets surrounding the Sun, but we can make some inferences about their past and future motions from mass-estimates and spectroscopy. There are professionals who study the interactions of local groups, clusters, superclusters, filaments, etc. We are humble short-lived humans and we have to make lots of inferences and extrapolations to model the behaviors of groups of galaxies because they move and interact on galactic (duh!) scales. We might be wrong a lot of the time, but by studying LOTS of interacting galaxies, and identifying outliers and chance projections, we should be able to learn more about their interactions from what are essentially snap-shots (images and spectroscopy from the last <100 years or so). There is a lot to learn about our universe that is not concerned with early-age cosmology or unification theories. Observational astronomy still has a place. If you are interested in astronomy and want to work in the field, there is room...
 
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FlexGunship
Gold Member
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Why don't galaxies for giant "solar systems"?
More precisely: why don't solar systems against small "galaxies"?


The name "solar system" implies that the star "Sol" is involved. Thus far, only one star has been named such. However, galaxies do not form into large planetary systems mostly because of the size and organizational structure.

In a way, however, you could make an argument that a spiral galaxy is similar to a planetary system. The net movement of the galaxy conserves angular momentum where possible like a planetary system. Orbits of stars around the gravitation center of a galaxy can be likened to the orbit of a planet around a star (however, galactic orbits are much more complicated because of the interplay of gravity inside the galaxy). And, like planetary systems, galaxies are most massive at the gravitational center (as would be expected).

EDIT: Also, the stars in a galaxy couldn't settle into mutually exclusive orbits. Firstly, a star is not massive enough compared to the other debris in the corresponding orbit (i.e. other stars). Furthermore, the time it would take for a star to orbit the galactic center enough times to clear a decisive orbit would be much longer than the lifetime of the star itself.
 
Sorry everyone, let me rephrase the question. I mean if our solar system was made from a disk of gas and rock, would galaxy eventually become similar to a solar system(a sun/core and several planets)?
 
mathman
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Galaxies have millions of suns, so it would be impossible to collapse into one solar system. The end result, if it were to occur, would be a gigantic black hole.
 
Chronos
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Processes similar to those that formed the solar system are believed to also be responsible for galaxy formation. We still, however, have a lot of unanswered questions. One in particular is the role of supermassive black holes. Nearly every galaxy of any size seems to have one of these beasts at its heart. We live in interesting times.
 
So if every galaxy has a super massive black hole at the center, would it be possible that each galaxy will be sucked into the black hole eventually?
 
russ_watters
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Not really - the stars are in orbit of the black hole.
 
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Why don't galaxies for giant "solar systems"?
Here is a generalization which ignores such things as captured moons and asteroids, supernovas, planetary collisions, galactic mergers, and density waves for the sake of simplification.


First, for a galaxy to be one gigantic solar system it would need a star in its center. What we have is a black hole.

Second, one huge galactic solar system cannot form because matter density is not equally distributed. Instead it forms clumps like in a cake batter mix. Such clumps attract more unevenly- distributed matter which itself forms smaller clumps. The bigger original clump collapses under its own gravity, nuclear fusion begins and a star is born. The surrounding less dense clumps also collapse under their own "weight" and become planets, moons, asteroids, Kuiper belts objects and all the other flotsam making up solar systems. Since this happens as the galaxy is forming its eventual configuration is never just one gigantic solar or black hole system with only stars in orbit.
 
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