Open star clusters are widely distributed in our galaxy and represent a loose collection of stars which number from a few dozen to a few hundred stars and are weakly-held gravitationally. Perhaps the three most famous such open clusters are the Pleiades (M45) in Taurus, the Beehive (M44) in Cancer and the double cluster in Perseus. They are all characterized with a handful of hot and white prominent stars and nebular material surrounding these stars.

Note: Although estimates vary dramatically, open cluster NGC 225 has been estimated to be anywhere from 10 to 120 million years old, thus making this widely dispersed cluster one of the youngest open clusters in the Milky Way. With approximately 20 bright member stars lying approximately 2140 light-years away, this cluster lies betwen γ-Cas (mag 2.17) and κ-Cas (mag 4.17). The cluster's discovery has been attributed to Caroline Herschel (1784) and is currently catalogued in multiple sources. Being effectively a circumpolar cluster, its observation is not dependent on season and/or time. It is of interest to note the presence of reflection nebulosity (see upper-right) and which is further indication of its very young age.