Superbubble is the astronomical term used to describe a cavity hundreds of light years across filled with 106 K gas blown into the interstellar medium by multiple supernovae and stellar winds. Sol lies near the center of an old superbubble, whose boundaries can be traced by a sudden rise in dust extinction of stars at distances greater than a few hundred light years. The most massive stars, with masses ranging from eight to roughly one hundred solar masses and spectral types of O and early B are… (More on Superbubble)