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Mass Density

(density of a volume of space)

Mass Density is a measure of the amount of matter in a volume of space. Some examples:

Medium equivalent Hydrogen atoms/meter³
Earth rock 1030
Earth Atmosphere at sea level 1026
Typical Interstellar Medium 1 to 1012
Typical Intergalactic Medium 1 to 50
Apparent Baryonic Density of the universe .2-.25
Critical Density 5
Apparent density w/Dark Matter etc. same

(astrophysics,measure)
http://en.wikipedia.org/wiki/Outer_space
http://en.wikipedia.org/wiki/Density_of_air

Referenced by:
Astronomical Quantities
Cluster Radius
Column Density
Critical Density (ρc)
Free-Fall Time
Jeans Length
Number Density
Vortensity (PV)

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