Each of the schools has its own role in the cluster.

They last 10 to 100 million years and are sometimes found in clusters.

The young men sat down around me in a close cluster.

There were three girls and one man in the cluster.

All stars are usually around the same age in a given cluster.

This is the reason why stars usually form in clusters.

Those homes were built in clusters of 12 to 50.

They appear in small clusters of 3-7 throughout the season.

Usually the sites in a cluster are within an hour's drive of each other.

Each flower in the cluster looks like a blue star.