Molecular clouds in deep space are fascinating objects. Various organic molecules have been found there (including alcohol, heh heh).

So if one of these clouds contained about 20% of oxygen, would it be possible to breathe it in the inner regions of the cloud?

  • $\begingroup$ The percent oxygen is not the important number for respiration, instead what matters is the partial pressure of oxygen which needs to be around 0.2 atm. $\endgroup$
    – Lex
    Oct 27, 2017 at 18:02

1 Answer 1


Not a chance.

Those "clouds" are a vacuum, but just a vacuum that has a few more particles than outside those "clouds". The density of those "clouds" around 1–100 particles per cm³. You can't breathe it at all.

You may want to look at this Scaling in Density page at Princeton University:

Earth: 5.5 gram/cm³, $1.8 \cdot 10^{23}$ molecules per cm³,

Earth atmosphere: 0.0012 g/cm³ (Wikipedia),

Molecular Clouds: $2 \cdot 10^{-22}$ gram/cm³, 10 molecules per cm³.


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