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Author Topic: Is there dark matter in the solar system?  (Read 3211 times)

Offline thedoc

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Is there dark matter in the solar system?
« on: 01/04/2012 10:40:01 »
Manogrie Golden  asked the Naked Scientists:
   Hello

I'd like to know if there is any dark matter in our Solar System, and if so, do we know what is its mass and where it is located?

Thanks!

Cheers,
Manoo Golden
(Johannesburg, South Africa)



What do you think?
« Last Edit: 01/04/2012 10:40:01 by _system »


 

Offline Ęthelwulf

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Re: Is there dark matter in the solar system?
« Reply #1 on: 01/04/2012 13:00:35 »
If we consider the usual definition - dark matter is a form of particles which do not interact Electromagnetically, then by it's purest definition, Neutrino's are in fact dark matter particles. We have not detected any other kind, yet.
 

Offline JP

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Re: Is there dark matter in the solar system?
« Reply #2 on: 01/04/2012 16:58:59 »
To understand the answer to this question, you first have to understand why we believe dark matter exists in the first place.  Essentially, we can observe the effects of gravity, so we know roughly how strong gravity is in the universe.  We also know that matter/energy is a source of gravity.  When we look at how strong gravity is around galaxies, we see that there isn't enough matter in the galaxies to account for it.  So the most obvious way of accounting for that is that there's some form of matter that we can't see with our telescopes.  Since telescopes work by detecting electromagnetic radiation (light, X-rays, radio waves, etc.), we postulate that this matter doesn't emit electromagnetic radiation (making it 'dark'), but that it does act gravitationally like other matter we know, which would account for the strength of gravity around galaxies. 

Dark matter is the most obvious explanation for the discrepancy between matter we see and the strength of gravity around galaxies, but we haven't seen dark matter in a lab yet (there's hope that building underground detectors might work, or that we might see it at the LHC).  If this hypothesis about dark matter is correct, then we can infer its mass and where it's located throughout the galaxy based on measuring the strength of gravity and comparing that to the visible matter in the area.
 

Offline syhprum

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Re: Is there dark matter in the solar system?
« Reply #3 on: 01/04/2012 20:30:38 »
Normal matter becomes "dark" if it is sufficiently compressed could it not be micro black holes
« Last Edit: 02/04/2012 07:09:15 by syhprum »
 

Offline imatfaal

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Re: Is there dark matter in the solar system?
« Reply #4 on: 02/04/2012 12:28:57 »
Normal matter becomes "dark" if it is sufficiently compressed could it not be micro black holes

Micro blackholes are short lived and very hot/bright (a/c hawking radiation).  Larger blackholes tend to have very hot and bright accretion disks and polar jets.

Neutrinos could be part of the answer (they would be hot dark matter) - but we would also need some other particles that are slow and cold
 

Offline Soul Surfer

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Re: Is there dark matter in the solar system?
« Reply #5 on: 02/04/2012 23:34:16 »
Yes and some attempts are being made to detect it.  If there is a flow of dark matter through the solar system the existing gravitational nodes (sun and planets) will cause it to vary very slightly in density.  This would mean that the local inverse square laws will not be absolutely accurate because of this tiny variation in the "density of space"  If this effect could be detected it could give a lot of useful information of the nature and temperature of whatever it consists of.
 

Offline grizelda

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Re: Is there dark matter in the solar system?
« Reply #6 on: 03/04/2012 05:00:54 »
Perhaps the Higgs field "borrowed" 5% or so of gravity to create mass. The remaining gravity would still be around to, say, pull spacetime flat after the mass that distorted it has moved on.
 

Online yor_on

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Re: Is there dark matter in the solar system?
« Reply #7 on: 03/04/2012 06:49:58 »
Maybe?
Does light have a mass?
Does light 'propagate'?

Etc :)

Eh sorry, but we only have about 5 percent of the universe defined as it seems?
Not much huh, and then 'bosons' of course :)
 

Offline Manoo

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Re: Is there dark matter in the solar system?
« Reply #8 on: 03/04/2012 11:04:42 »
Hello

I was wondering if the reason that we have not been able to detect dark matter is because it may exist in other spatial dimensions; but through which we can still detect its gravitational effects?

Manoo
 

Offline graham.d

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Re: Is there dark matter in the solar system?
« Reply #9 on: 03/04/2012 11:15:14 »
Models of dark matter around galaxies that fit in with observations (the relationship between the velocities of stars at various radii from the galactic centre - see virial theorem) show an almost spherical distribution around the galactic disc that spreads some distance beyond the disc itself. This gives a very low, but even density of dark matter, which would mean that there is no reason to suppose that it would excluded from our solar system. The density is very low though, and because it is thought to only interact with other matter gravitationally, it is very hard to detect by any localised measurement.
 

Offline Soul Surfer

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Re: Is there dark matter in the solar system?
« Reply #10 on: 04/04/2012 11:22:11 »
The difficulty of detecting particles that interact only by gravity is incredibly difficult.

They would fly through normal matter just like it wasn't there even super dense material like neutron stats would hardly affect their progress.

Even if they were particles and antiparticles (which they probably are) they would collide so infrequently that they would be almost undetectable except by their collective gravitational field which is currently the way they are detected. 

My guess is that they are what is sometimes called sterile neutrinos or what I would prefer to call gravitinos that is particles with spin but no charges of any kind.  This means that they occupy space and if formed in close proximity to each other would tend not to collapse but push each other apart and could even account for expansion processes.
 

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Re: Is there dark matter in the solar system?
« Reply #10 on: 04/04/2012 11:22:11 »

 

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