1. The Big Bang Theory + Star Life Cycles + HR Diagram

2. Big Bang Theory About 14 billion years ago, the universe began as a hot dense ball of energized matter The ball expanded allowing the matter to cool and eventually form the atomic particles (protons, neutrons, and electrons) These particles gather together via gravity to form the first stars and galaxies

3. Big Band Theory Evidence – Galaxies are moving farther away – Lots of “light” elements – Supernovae are doing the same thing to form new stars and galaxies

4. Big Bang Theory Questions? Another explanation: http://www.khanacademy.org/science/cosmol ogy-and-astronomy/universe-scale-topic/big- bang-expansion-topic/v/big-bang-introduction http://www.khanacademy.org/science/cosmol ogy-and-astronomy/universe-scale-topic/big- bang-expansion-topic/v/big-bang-introduction