Galactic Dust and Nebulae

How big are molecular clouds?

Molecular clouds can be enormous compared to stars. The largest ones are called “giant molecular clouds” and can be many light-years across. Giant molecular clouds can contain thousands or even millions of times as much mass as the Sun; they may also contain a number of dense core regions, each with one hundred to one thousand Suns’ worth of gas. This is the raw material needed to build entire clusters of new stars.


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