Structure of the Milky Way?

  • #1
I and a few friends thought about the oort cloud...
If it has 2 light years in lenght, that's half way to Alpha Centauri...
What would stop our near neighbor Alpha Centauri to have its own oort cloud...
And if this is wright couldn't the galaxy be filled with dwarf planets, asteroids and comets rather than empty space between the stars as usual sci-fi movies like to show?
 

Answers and Replies

  • #2
Yes the galaxy is filled with asteroids, comets and dwarf planets, but that doesn't mean that you would bump into one celestial body after another when passing through it. The distances between these objects are so enormous that you would have to carefully aim in order to hit something. The sci-fi movies actually got it right. The space is mostly empty.
 
  • #3
Could we actually Colonize some of those wild planets... if they are big enaugh?
i mean i think they can get to the size of Earth or biogger, no?
 
  • #4
^ Spell check.

It's not very easy to answer speculative questions. The Kepler satellite is searching for Earth-sized planets, so if we were to ever colonize a planet, it would more than likely be a planet similarly sized to Earth (obviously).
 
  • #5
Could we actually Colonize some of those wild planets... if they are big enaugh?
i mean i think they can get to the size of Earth or biogger, no?
Do you mean a rogue planet? As in a planet-sized object not anywhere near a star? They'd be far, far too cold to colonize.
 
  • #6
Do you mean a rogue planet? As in a planet-sized object not anywhere near a star? They'd be far, far too cold to colonize.
Oke...
Cold let it be, we could have hitting systems inside huge metropolises covered by some kind a dome but not made of glass as it is too fragile...
or we could make a strong enaugh glass so we could also se the galaxy trough it...
eeeeeh... this kind a colonization is more for fun... imagine this small scene: in the darkness of space in a huge cluster of planets, Dwarf and partially borken planets, dwarf planets, comets and asteroids surrounded by a shinning blue nebula but thin enaugh to se the galaxy trough the glass domes of our colonies... wouldn't that be nice:approve: even spectacular if i say so...:tongue:
man this chat is more because I'm REAAAAAAALLY bored
 
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  • #7
Oke...
Cold let it be, we could have hitting systems inside huge metropolises covered by some kind a dome but not made of glass as it is too fragile...
or we could make a strong enaugh glass so we could also se the galaxy trough it...
eeeeeh... this kind a colonization is more for fun... imagine this small scene: in the darkness of space in a huge cluster of planets, Dwarf and partially borken planets, dwarf planets, comets and asteroids surrounded by a shinning blue nebula but thin enaugh to se the galaxy trough the glass domes of our colonies... wouldn't that be nice:approve: even spectacular if i say so...:tongue:
man this chat is more because I'm REAAAAAAALLY bored

Did you have a specific question?
 
  • #8
Oke...
Cold let it be, we could have hitting systems inside huge metropolises covered by some kind a dome but not made of glass as it is too fragile...
or we could make a strong enaugh glass so we could also se the galaxy trough it...
It's more a problem of having the energy to actually do anything.

Maybe if we solve the problem of getting nuclear fusion reactors off the ground, maybe it will be possible. But why bother with that when there are likely to be billions of candidate planets in our galaxy within the habitable zones of stars?
 
  • #9
It's more a problem of having the energy to actually do anything.

Maybe if we solve the problem of getting nuclear fusion reactors off the ground, maybe it will be possible. But why bother with that when there are likely to be billions of candidate planets in our galaxy within the habitable zones of stars?

True, but the majority of those candidates are planets found in the solar system of a red dwarf, which means that the habitable zone of these planets is required to be a lot closer than the Earth is to our sun, which opens up complications like harmful radiation.

Then again, once we get to the point where we can colonize other planets, I doubt we would want to be too picky :)
 
  • #10
True, but the majority of those candidates are planets found in the solar system of a red dwarf, which means that the habitable zone of these planets is required to be a lot closer than the Earth is to our sun, which opens up complications like harmful radiation.

Then again, once we get to the point where we can colonize other planets, I doubt we would want to be too picky :)
Well, that's more a feature of the fact that it is technically more difficult to detect planets which have orbits closer to one year here on Earth than it is to detect these closer-in planets. I doubt that there is any real bias towards red dwarfs where habitable-zone planets are concerned.

Of course, most stars out there are red dwarfs, but there are one heck of a lot of yellow dwarfs around as well.
 
  • #11
It's more a problem of having the energy to actually do anything.

Maybe if we solve the problem of getting nuclear fusion reactors off the ground, maybe it will be possible. But why bother with that when there are likely to be billions of candidate planets in our galaxy within the habitable zones of stars?

For posterity man!:biggrin:
To show the galaxy how kool can we get:approve:

I agree with you, Chalnoth,
But couldn't we colonize a few planets that orbit around Blue giant stars?
If there are any solid ones... or...:confused:
 
  • #12
For posterity man!:biggrin:
To show the galaxy how kool can we get:approve:

I agree with you, Chalnoth,
But couldn't we colonize a few planets that orbit around Blue giant stars?
If there are any solid ones... or...:confused:
Well, blue giants tend to have rather short lifetimes, and when they die they explode in massive supernovas. So they would be rather hazardous places to live.

Yellow dwarfs, like our own sun, are pretty much ideal. Much smaller, and they are quite volatile when young and the habitable zone is in very close to the star, making it unlikely that they have genuinely habitable planets. Much larger, and the lifetime of the star shortens significantly, often with many rather violent episodes before the final supernova. Yellow dwarf stars, though, last quite a long time (billions of years) and are relatively quiescent.
 
  • #13
Well, blue giants tend to have rather short lifetimes, and when they die they explode in massive supernovas. So they would be rather hazardous places to live.

Posterity, remember let's harvest some adrenaline...:biggrin:
Till the time comes when we could even control a supernova or just live trough the exploding giant we are most surely going to search for planets orbiting yellow dwarf and red dwarf stars...

But hey... a small imaginary jump in the future jus may feed our will to explore space and get us a bit a fun!:approve:

(In the future we would have colonized planets that have close orbits to black holes...:tongue:)
 
  • #14
one thing that i don't understand... Why are there more red dwarfs than any other type of stars?
 
  • #15
one thing that i don't understand... Why are there more red dwarfs than any other type of stars?

because they spend a very long time as red dwarfs, whereas giant stars don't last very long
 
  • #16
one thing that i don't understand... Why are there more red dwarfs than any other type of stars?

because they spend a very long time as red dwarfs, whereas giant stars don't last very long

That plus red dwarfs are very easily made as they require much less material than larger more massive stars. When stars form from a collapsing gas cloud you typically have many more small stars created than larger stars.
 
  • #17
Posterity, remember let's harvest some adrenaline...:biggrin:
Till the time comes when we could even control a supernova or just live trough the exploding giant we are most surely going to search for planets orbiting yellow dwarf and red dwarf stars...

But hey... a small imaginary jump in the future jus may feed our will to explore space and get us a bit a fun!:approve:

(In the future we would have colonized planets that have close orbits to black holes...:tongue:)

I don't understand your reasoning at all. Isn't the idea of colonizing other planets far-fetched enough for now? Let alone colonizing unfavorable and unforgiving planets near black holes?

It's good to be excited about these things, but you need to stay slightly realistic. If the only reason to inhabit certain areas of the universe is just for the hell of it, or just to show that we can, then I think we would need to question the intelligence of the people authorizing those missions.
 
  • #18
one thing that i don't understand... Why are there more red dwarfs than any other type of stars?
Smaller objects tend to be far, far more numerous than larger ones.
 
  • #19
We should never colonize planets outside our own solar system. Expansionism unavoidably leads to war. And war with a high technology level likely leads to extinction for all sides involved.
I know that doesn't sound good for SF movies and for people's imagination, but it's closer to reality.

On the other hand, small outposts can be built anywhere. But why on a rogue planet in the middle of nowhere ?
 
  • #20
We should never colonize planets outside our own solar system. Expansionism unavoidably leads to war. And war with a high technology level likely leads to extinction for all sides involved.
I don't quite see why. It's highly unlikely that we'd ever run into another space-faring civilization, if it is even technically possible to expand beyond our own solar system. Because if such civilizations were that common, they'd probably already be here.
 
  • #21
I don't quite see why. It's highly unlikely that we'd ever run into another space-faring civilization, if it is even technically possible to expand beyond our own solar system. Because if such civilizations were that common, they'd probably already be here.

Not only they would probably be here already, but if they had the same thinking the humans do, we would have been extinct and Earth would have been an alien colony. The same reasoning applies to having contacts with aliens at any point in our future. Expansionism unavoidably leads to confrontation.
 
  • #22
We should never colonize planets outside our own solar system. Expansionism unavoidably leads to war. And war with a high technology level likely leads to extinction for all sides involved.
I know that doesn't sound good for SF movies and for people's imagination, but it's closer to reality.

On the other hand, small outposts can be built anywhere. But why on a rogue planet in the middle of nowhere ?

And that would leave us with, what? Mars and maybe some moons to colonize?

Hopefully by the time we're advanced enough to colonize other planets or solar systems, war would have become a thing of the past. Probably not, but one can dream.
 
  • #23
Do Red Dwarf Systems tend to have more solid planets?
And can there start evolving life in any of these systems?
And another question: If a nebula has about 100 or more light years in diameter and if it is very thick and mostly composed out of H2 what type of stars tend to take birth in there?
And can they have solid planets rather than gas giants?
 
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  • #24
I don't understand your reasoning at all. Isn't the idea of colonizing other planets far-fetched enough for now? Let alone colonizing unfavorable and unforgiving planets near black holes?

How would they be unforgiving? The only dangerous situation would be if the accretion disc or the jets gets to be a problem (only valid if it's swallowing something) or if someone flies a spaceship directly into a black hole, or if the minor time dilation from being a bit closer to the black hole might throw people out of whack. GR says that a freefalling observer is locally inertial (right?)
 
  • #25
On the other hand, small outposts can be built anywhere. But why on a rogue planet in the middle of nowhere ?

For fun!
And for the beauty of it...
Imagine... One can look up the glass dome of a city build on the surface of a rogue planet in a cluster of those planets surounded by a thin blueish nebula and the sky allways filled with tousands of stars cause of the lack of atmosphere...
Wouldn't that be epic?:rolleyes:
 
  • #26
Do Red Dwarf Systems tend to have more solid planets?
And can there start evolving life in any of these systems?
And another question: If a nebula has about 100 or more light years in diameter and if it is very thick and mostly composed out of H2 what type of stars tend to take birth in there?
And can they have solid planets rather than gas giants?

Can someone read this questions?
 
  • #27
Our knowledge of extrasolar planets is very limited. Even more so, that of rocky planets. Rocky planets are extremely difficult to detect with current technology, as they're too small.

So it's hard to answer if red dwarfs tend to have more solid planets or not. They do have less giant planets.
There are many problems with habitability around red dwarfs:
http://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems
 
  • #28
-And can there start evolving life in any of these systems?
-And another question: If a nebula has about 100 or more light years in diameter and if it is very thick and mostly composed out of H2 what type of stars tend to take birth in there?
And can they have solid planets rather than gas giants?
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and what about this?
 
  • #29
"-And can there start evolving life in any of these systems?"
Because of the habitability problems explained on that wikipedia page, advanced life is less likely to evolve than around Sun-like stars.

"-And another question: If a nebula has about 100 or more light years in diameter and if it is very thick and mostly composed out of H2 what type of stars tend to take birth in there?
And can they have solid planets rather than gas giants?"
I don't know what kind of stars would take birth in that nebula. However, it will certainly have some amounts of heavier elements, so rocky planets are possible.
Whether a planet is rocky or not, is mostly about its size. Small planets won't be able to hold their hydrogen and helium, so they'll become rocky.
Larger planets, gas giants, still have rocky interiors, of various sizes.
 
  • #30
Whether a planet is rocky or not, is mostly about its size. Small planets won't be able to hold their hydrogen and helium, so they'll become rocky.
Well, you actually have to have the light elements blown away by the star in order to form a rocky planet. Otherwise you'll just get a gas giant with a rocky core.
 
  • #31
But, a huge gas giant could be perturbed into a tighter orbit after it had already formed. Its massive gravity would slow loss of its atmosphere for a long time.
 
  • #32
But, a huge gas giant could be perturbed into a tighter orbit after it had already formed. Its massive gravity would slow loss of its atmosphere for a long time.

How long will keep it's atmosphere?
Tousands, M\Hundreds of tousands, Millions, Tens of millions of years... BILLIONS?:confused:
 
  • #33
Otherwise you'll just get a gas giant with a rocky core.

but Would't the rocky core get crushed under the mass of the atmosphere and become a liquid... Or diamonds if it has a significant amount of carbon?
 
  • #34
"
"-And another question: If a nebula has about 100 or more light years in diameter and if it is very thick and mostly composed out of H2 what type of stars tend to take birth in there?
And can they have solid planets rather than gas giants?"

I don't know what kind of stars would take birth in that nebula.

If the nebulla is so thick and mostly composed out of H2 wouldn't there be a significant amount of Blue giands or super giants of stars as there is plenty of material to form out of?
 
  • #35
"How long will keep it's atmosphere?
Tousands, M\Hundreds of tousands, Millions, Tens of millions of years... BILLIONS?"
Billions of years, at least. There are plenty of examples of gas giants that orbit their stars very closely. It is assumed they formed further away and they later migrated closer to the star.

"but Would't the rocky core get crushed under the mass of the atmosphere and become a liquid... Or diamonds if it has a significant amount of carbon?"
Yes, because of the very high amounts of pressure, it will change its state. I don't know if it will be molten or not.
But that happens in the core of our planet as well. The very core of our planet is solid, surrounded by a larger, molten region. So at extreme pressures you can get a solid core even with very high temperatures.
 

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