Modifies a noun

• cloud: Dark interstellar clouds are believed to be where new stars are formed.

• spaceship: You will find yourself in a vast interstellar spaceship that has gone out of control.

• dust: Also visible are dark patches of interstellar dust which block our view of the stars behind them.

• grain: The sample return objective for fresh interstellar grains is to collect over 100 particles in the 0.1 micron to 1 micron size range.

• medium: The interstellar medium makes up between 10 to 15 % of the visible mass of the Milky Way.

• absorption: These sources are mostly detected below 0.5 keV, and so those in our Galaxy are mostly hidden by interstellar absorption.

Used with adjective complement

• go: It took a while for the public to catch on, but they now have and The Futureheads are about to go interstellar.