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MightyManfredTWD
2009-Apr-09, 09:15 PM
Somewhere in life it seems like I was told that the mass of all the difuse dust & gas in our solar system has greater total mass than all the planets & moons in our solar system put together. Is that true? If it is true, is it also true for our galaxy? Our universe??
Thanks again,
Manfred

Wizard From Oz
2009-Apr-09, 09:55 PM
With in the solar system I cant really say. However it may well be true. The Oort cloud for instance is a massive unknown in terms of mass and size. Then there is the Trans Neptunian objects, the asteroid belt etc etc. So yes there is an awful lot of junk out there.

With galaxies however I dont believe there is a rule of thumb equation, and you have to consider each galaxy on its merits. The figure for the Milky Way changes constantly as we refine out abilty to observe our home galaxy. I believe the ratio at the momment is considered to be about 50/50

Now to make it more interesting. The type of galaxy can affect the amount of gas and dust. Example some irregular galaxies have as much 90% gas and dust, the bigger elipitical galaxies appear to have very little gas and dust.

Then we have the issue of dark matter lol. So in essence there is no universal average you can try and apply

MightyManfredTWD
2009-Apr-09, 11:26 PM
Thanks Wizard. By "dust" I am thinking of particles the size of a "pebble" and smaller.
I'm kind of 50/50 on the "dark matter" thing. It may very well exsist, but I have a problem with the following thinking or math procedure:
"We believe that our math formula is correct, but it doesn't work out right. Therefore we will simply 'make up' something that we cannot see, feel, measure, touch, hear or smell, put that 'stuff' in the formula & that makes it correct."
In simple terms we have a formula:
3 + 5 = 12
Since 3 +5 DOES NOT equal 12 then we add 4 "nothings" to the left side of the formula, violating all rules of math, but it "looks good".
Then our formula looks like:
3 + 5 + 4 "nothings" = 12
I'm a bit of a skeptic.
Thanks again, Wiz
Manfred

loglo
2009-Apr-10, 12:47 AM
There is nothing magic about dark matter, the observations are repeatable and the conclusions pretty solid. We even have known types of dark matter called neutrinos. Its just that neutrinos don't fit the affect we see.

'So no magic, no dodgy maths and no wishful thinking, just solid science..... unless you have something more than just handwavy intuition to convince us.

MightyManfredTWD
2009-Apr-10, 12:54 PM
Thanks for the info on Dark Matter. Does anyone know if I am correct about the mass of the dust & gas in our solar system?
Thanks again,
Manfred

slang
2009-Apr-10, 01:21 PM
Wiki says about 5 earth-masses in the Oort cloud (http://en.wikipedia.org/wiki/Oort_cloud) (but earlier thought to be 380), 0.1 earth mass in the Kuiper Belt (http://en.wikipedia.org/wiki/Kuiper_belt) (but simulations requiring 30), so if those would be the major contributors, the answer would be no. Maybe you can search for interplanetary environment and find some density numbers. Going from that you might calculate a mass.

BigDon
2009-Apr-10, 01:48 PM
I thought I read though that the initial cloud o' gas we condensed from was approximately three solar masses? And that in five billion years we've long since drifted away from the remnants?

Wizard From Oz
2009-Apr-10, 04:05 PM
I thought I read though that the initial cloud o' gas we condensed from was approximately three solar masses? And that in five billion years we've long since drifted away from the remnants?

I am not sure about the initial starting mass, however the number of young stars we see with evidence of veiled gas strutures around them would suggest the second part of your answer is pretty correct. Aside from drifting, the star would also actively push this material away with solar winds etc

MightyManfredTWD
2009-Apr-12, 04:21 PM
Thanks folks~! Sounds like there isn't nearly as much diffuse dust & gas in our solar system as I was once told.
Thanks again,
Manfred

cjameshuff
2009-Apr-12, 06:04 PM
Thanks folks~! Sounds like there isn't nearly as much diffuse dust & gas in our solar system as I was once told.

Not in our solar system, the cloud that formed it has been pretty well cleared out by the sun and planets, either fallen into one of the forming bodies or thrown out of the system. There's still some around, though, enough to be visible under the right conditions: http://en.wikipedia.org/wiki/Zodiacal_light

The Milky Way galaxy as a whole has a reasonably large gas and dust content...4-5%, IIRC, enough to obstruct our view through the disk in visible and UV wavelengths...infrared and radio can penetrate the dust:
http://en.wikipedia.org/wiki/File:Ssc2008-11a.jpg

Some other galaxies have more gas and dust than they do stars. What you were told may have stemmed from a misunderstanding about one of these cases.

Jens
2009-Apr-13, 04:37 AM
While I don't know if this is true, what I've heard said in discussions on the problem of angular momentum is that 99% of the mass of the solar system is in the sun. This site (http://www.astro.ubc.ca/people/skaret/ast310/ss.htm) says that the sun has 99.86% of the mass of the solar system.