Universe Page 23
The universe is literally everything that exists. Some scientists and many people believe that the universe was created in a "big bang" many billions of years ago. In the universe there are billions of galaxies and each galaxy contains billions of stars. The universe is constantly being created and destroyed by star formation and black holes. Big Bang Theory holds that the universe was extremely small and exploded in a split second. A galaxy is a space system made up of gas, dust, and stars.