An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time . THE CHANGING UNIVERSE: EVOLUTION HAPPENS! . b) Changes in Stars . One of the great discoveries of modern science is that stars (like people) live only a measurable life-time and then die. Although the lives of the stars are enormously longer than the span of a human life, we can learn about the life story of the stars by studying them at many different stages in their life cycle, from birth to death. ...