STAR GROUPS—CLUSTERS

Here and there throughout the sky are places where the brighter stars seem to be clustered. These families of stars are of such magnificent proportions as to stagger the imagination. Among the best known are the Pleiades, the Hyades, Coma Berenices and Orion. Although they appear to us very close together, they are not really so, being usually several hundreds of thousands of miles apart. Many of these star-groups are irregular; but numbers of them constitute clusters, which are of various sizes and shapes. Perhaps the most interesting are the so-called “globular clusters,” because they present the appearance of stars having been massed together as globes. Some of them contain five or six thousand stars. Although they appear to us so close together, it has been calculated that, in a cluster containing 5,000 stars the average distance of the stars from one another would be 30,000 times the distance of the sun from the earth! The vast distances of space considered in astronomy may perhaps be realized by this fact—when it is considered that such a cluster appears to us as a single star, only capable of being separated into its component parts by means of high-powered telescopes!