A massive ensemble of hundreds of millions of stars, all interacting through the gravitational force, orbiting around a common center.<ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref> | A massive ensemble of hundreds of millions of stars, all interacting through the gravitational force, orbiting around a common center.<ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref> |