The gas/dust looking thing in the galaxies

[Skeptica]

Our sun is only 8 minutes away, and it looks like the size of a quarter. In comparison to the sun, the earth probably looks like a grain of sand. When we hurl the sun to 12 billion light years away, the earth probably looks like an element of gas. So, what are those dust/gas looking thing in the galaxies? Are they more like the earth, the moon, or comets? They can't be dust, can't they? Visible dust at 12 billion light years distance has got to be huge.

Patrick

 

[origin]

You are right that of course there is no way that we could see dust grains at that distance. What you are seeing is several different dust clouds that block the light from parts of the galaxies. A simple anology are clouds in the atmosphere - you cannot of course see the individual water vapor dropplets but clouds still block out the sun light on a cloudy days. Dust and gas clouds can be huge, and it is the effect of many different dust and gas clouds that cause the mottled apperance of the galaxies.

 

[adrenalynn]

Actually - most aren't really obscuring light. That's what "Dark Nebula" (like the Horsehead in Orion) does. Many that we see are emission nebula. The gasses are glowing.

 

[origin]

Actually - most aren't really obscuring light. That's what "Dark Nebula" (like the Horsehead in Orion) does. Many that we see are emission nebula. The gasses are glowing.

I don't think that is right - I of course could be wrong. But my rational is that when we look at the milkyway we do not see a that many of the stars in the galaxy because of the dust, atoms, and molecules in the inervening space, and the emission neubula are fairly few and far between. I may have mislead by my characterization of the dust as 'clouds' when I was refering to galactic dust in general.