interstellar matter
Quick Summary
The interstellar medium is the region between stars filled with diffuse clouds of gas and dust. In our Milky Way galaxy, this tenuous matter makes up about 5 percent of its total mass. Primarily composed of hydrogen gas, it also contains helium and smaller amounts of other substances like calcium, sodium, water, ammonia, and formaldehyde, along with dust particles.1
This matter often forms cloudlike concentrations that can condense to create stars. Stars, in turn, release mass back into the interstellar medium through eruptions or supernovae, contributing to the circulation of matter that influences the abundance of heavier elements in cosmic clouds. The interstellar medium is studied using optical and radio telescopes, with infrared telescopes also contributing to our understanding of its properties.1
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