They are tight groups of stars that are held together by Gravitational force. They are about 10,000 million and are old stars.
Open Clusters
They are loosely situated in a group. They are about lesser than a few hundred and are usually young stars.
Let us see the 5 clusters seen from the earth:
Usra Major Cluster
It is the closest cluster to us. We can spot them every night of the year by looking to the north of the sky.
Coma Star Cluster
It is a group of 50 stars which is located about 300 light-years from us.Comma star cluster can be seen on the spring nights on the eastern side of the sky.
This is 1000 light-years away from us. With naked eyes, we can only see them during clear nights from October to May.
Orion’s Head
Alpha Persei Cluster
It is about 600 light-years distant. From late summer to autumn is the best time to spot this cluster.
Double Cluster
They are present every night of the year. They are in the far northern part of the sky.