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Interstellar medium

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What is the Interstellar Medium?

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5 Things About Interstellar Space

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Interstellar Medium : A Brief Explanation

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Interstellar Medium - Back to the Good Times

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An introduction to the interstellar medium

In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field.