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Since outer space is not quite a vacuum, and the distribution of various heavenly bodies is locally inhomogeneous, it seems reasonable to expect that the density and variety of particles 'contaminating' the vacuum varies with time and space. Are there any maps or data sets which detail this variation?

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Depends on at what scale you are talking about.

Our galaxy is mostly vacuum, but we have a really good idea of where the mass lies within the galaxy.

Map of the milky way

This is a multi-wavelength image of the whole sky, and the blue band in the centre is the galactic plane, and the blue hazy structures are gas and dust from the galaxy.There are several other ways to map out the mass distribution in our galaxy, like the galaxy rotation curve.

If you're talking about mass distribution on the scale of the universe, that's a much more complicated question. It's a lot tougher to see small objects really far away. So we tend to see only the really big ones, and given how large the universe is, sometimes it's hard to notice the really big ones if they aren't bright enough to be seen. (Note - Because the universe is expanding, if something is far away, it is also older. And far away things suffer from cosmological dimming, hence the brightness constraint).

But there is a map of the Cosmic Microwave Background radition (CMB radiation) that's been made


As the wikipedia article I linked to explains in more detail - The small scale variations in this map give us an idea of how mass is/was distributed in the universe. A few really high redshifted (really old) galaxy clusters have been discovered through CMB anisotropies. This happens through a process called the SZ Effect, which is a pretty cool effect.

I've probably missed out on a few other ways of estimating mass, but these are the observational ones that I know about.

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This is a short answer, but there are some direct observation maps as well as simulations. As noted, the particles are largely called "gas" although the molecular/atom separation is obviously much larger than what we see in day to day life here on earth.

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