Labels:text | screenshot | font | number OCR: FACT FILE THE INTERSTELLAR medium (ISM) makes up about 10 percent of the mass of the Milky Way Galaxy, and this figure is typical for spiral galaxies. Much of the interstellar material in spiral galaxies is located in the arms, in regions where star formation is taking place. Elliptical galaxies contain little if any interstellar material because it has all been used to form stars.
