Stellar Evolution and Classification

You have now learned about the birth, life, and death of stars. Stars begin in a nebula, and then travel through a very long life cycle, until they end up as a white dwarf, supernova, neutron star, or black hole. All types of stars can be classified and represented on the Hertzsprung-Russell diagram. On the H-R diagram, the Sun is a middle-aged, medium luminosity star. The hottest stars are blue and the coolest stars are red. Stars can occur in pairs called binary stars or as large groups called clusters. Constellations are groups of stars as seen from Earth that were used by ancient societies. Perhaps the most amazing thing about studying stars is that they are so far away, and by the time the light from some stars reaches Earth, the star has already burned out. In this way, looking at the stars is like looking back through time!