Airs Tuesdays at 9pm/8c on HISTORY. They are the one-stop-shopping places for learning all about the nature and variety of stars in the Universe. Theyre unique, because in clusters, all the stars were born at about the same time, from the same material and all are at the same approximate distance from Earth. This means we can be sure that any differences among them are due to their true natures and not distorted by different distances from Earth and other factors. In this episode, two kinds of star clusters in the galaxy are explored. Visit the official fan page at http://facebook.com/TheUniverse, follow HISTORY on Twitter at http://twitter.com/History_Daily and visit the official website at http://history.com/theuniverse.