Open clusters are stellar nurseries. They consist of just a few hundred relatively young stars. We have cataloged thousands
of this type of cluster in just our local region of the Milky Way galaxy alone. Thousands more must exist throughout the entire
galaxy. The most famous of these clusters is the Pleiades, or Seven Sisters. This grouping of stars is visible in all but the
most light-polluted skies. The Japanese call this cluster Subaru; yes, like the car name. The Subaru logo is this star cluster
stylized. Another well-known object is the Double Cluster in the constellation of Perseus.
Since we can make the assumption that all of the stars in an open cluster were formed at essentially the same time, and are
approximately the same chemical composition and the same distance from us, when we plot the member stars on a color
magnitude diagram, we can learn much about the evolution of the cluster.