In astronomy, the interstellar medium (ISM) is the matter and radiation that exist 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 difference is the measure of time. Weather is the short-term conditions of the atmosphere. Climate is the average daily weather but for an extended period of time at a certain location.
