Astronomers have deciphered the formation history of young star clusters, some of which we can see with the naked eye at night. The team reports that most nearby young star clusters belong to only three families, which originate from very massive star-forming regions. This research also provides new insights into the effects of supernovae (violent explosions at the end of the life of very massive stars) on the formation of giant gas structures in galaxies like our Milky Way.