interstellar medium

British  

noun

1.  ISM.  the matter occurring between the stars of our Galaxy, largely in the spiral arms, and consisting mainly of huge clouds of ionized, neutral, or molecular hydrogen

---

interstellar medium Scientific  

/ ĭn′tər-stĕl′ər /

1. Material, mostly hydrogen gas, other gases, and dust, occupying the space between the stars and providing the raw material for the formation of new stars. Nebulae are the most distinct areas of the interstellar medium; they appear when the clouds of gas and dust cluster due to interaction with nearby stars or star remnants.

---

Example Sentences

This allowed scientists to map everything from dust in the interstellar medium to the largest scale of structure in the universe, galaxy clusters.

From Los Angeles Times • Aug. 2, 2024

“It is surprisingly difficult to observe the interstellar medium that is just outside of our heliosphere.”

From Science Magazine • May 23, 2024

Astrospheres, stellar analogues of the heliosphere that surrounds our solar system, are very hot plasma bubbles blown by stellar winds into the interstellar medium, a space filled with gas and dust.

From Science Daily • Apr. 12, 2024

“A comet traveling through the interstellar medium basically is getting cooked by cosmic radiation, forming hydrogen as a result,” Dr. Bergner said in a statement issued by the University of California, Berkeley.

From New York Times • Mar. 22, 2023

From the phenomena of sound, as displayed in the air, they ascended to the phenomena of light, as displayed in the aether; which is the name given to the interstellar medium.

From Fragments of science, V. 1-2 by Tyndall, John