... The stars are not alone. In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM). ... PKS 1127 145: Quasar View . ... Giant Storm Systems Battle on Jupiter . ... Each of these galaxies houses billions of stars - just as our own Milky Way Galaxy does. ... Cen A is a giant elliptical galaxy a mere 10 million light-years distant with a central jumble of stars, dust, and gas that probably hides a massive black hole. ...