AST-1002 Chapter 12: Chapter 12 Notes
Document Summary
We can see a relatively small amount of it through visible light telescopes; however, the bulk of it is too cold to be seen optically and requires the use of infrared and radio telescopes. We call all the matter between stars the interstellar medium, and it contains at least. 10% of the observed mass in our galaxy. Observations of the spectra of the interstellar medium reveal that it is composed of gas containing isolated atoms and molecules and tiny pieces of dust. When it can be seen in the visible part of the spectrum, the gas and dust in the interstellar medium glow as a result of scattered light from stars in its vicinity. As another example, the interstellar medium is dramatically highlighted by stars in the. Pleiades star cluster located in the constellation taurus. The bluish haze, starlight scattered by the interstellar gas and dust, is called a reflection nebula.
