posted by Shirley .
How does the mass of all the interstellar matter in our galaxy compare with the total mass of its stars?
Physical Science -
If you include dark matter, which is poorly understood and invisible, and makes up about 90% of the total Milky Way's mass, there is more interstellar matter than stars within our galaxy.
However, the total mass of interstellar gas and dust is a few percent of the total mass of stars, according to what I can find by searching the web.