"The rich variety of stars live in our Galaxy mostly singly or in pairs ... Sometimes, however, hundreds or thousands of stars can be found in loose groups called s. The is a daily young open closer, and the which surrounds the famous "seven sisters" of this cluster attests to the fact that these stars must only recently have been born out of the surrounding gas and dust. The oldest stars in our Galaxy are found in tighter groups called s. Rich globular clusters may contain more than a million members."