Crash Course Astronomy | Low Mass Stars: Crash Course Astronomy #29 | Episode 29 | PBS

Today we are talking about the life -- and death -- of stars. Low mass stars live a long time, fusing all their hydrogen into helium over a trillion years. More massive stars like the Sun live shorter lives. They fuse hydrogen into helium, and eventually helium into carbon. When this happens they expand, get brighter, and cool off, becoming red giants.