Messier 7: Ptolemy’s Cluster
Messier 7 (M7), also known as Ptolemy’s Cluster, is a bright open cluster in Scorpius constellation. The cluster lies at an approximate distance of 980 light years from Earth. It has the designation NGC 6475 in the New General Catalogue. With a visual magnitude of 3.3 and an apparent diameter of 80 arc minutes – more than twice the apparent size of the full Moon – Ptolemy’s Cluster is an easy naked-eye target.
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