The interstellar medium is an extremely sparse (tenuous) mix of gas and dust, some of the gas being ionized, some atomic, and some molecular. By composition the gas is largely hydrogen, with smaller amounts of helium and very small amounts of heavier elements. There are also cosmic rays which are protons and nuclei which have been accelerated to near-relativistic speeds.
In cooler, high-density areas, the interstellar medium can become as dense as one ten-billionth that of air.
Interstellar gas is made of mainly hydrogen. This is because that is the building for everything and hydrogen is the most common element in the universe.
protostar or nebula
by the winds of massive stars and supernovae
The word 'interstellar' in a sentence: The interstellar nebula was huge compared to the asteroid.
Strontium is an element it is made in stars and is blasted into the interstellar medium when stars explode. It can also be made in Human nuclear reactors.
Asteroid belt. They are not "interstellar", of course.
Brian M. Cancellieri has written: 'Interstellar medium' -- subject(s): Interstellar matter
An interstellar cloud made of gas, dust, and plasma in a galaxy.
Interstellar gas is made of mainly hydrogen. This is because that is the building for everything and hydrogen is the most common element in the universe.
Kenneth Borg has written: 'Computations on interstellar extinction' -- subject(s): Interstellar matter, Optical properties
Visible light against electrons combined with ionized hydrogen create the "reddening" effect in the Interstellar Medium.
W. B. Burton has written: 'The galactic interstellar medium' -- subject(s): Astrophysics, Interstellar matter, Molecular clouds
The Asteroid Belt
protostar or nebula
Interstellar matter floats around, and if enough of it coalesces, then it can turn into a new star or cluster of stars.
by the winds of massive stars and supernovae
Interstellar is when the extinction of things goes interstellar.