Broader view of M7, the cluster is at the center of this photograph. Image source: (1)
Until now, all the objects in the Messier Catalog had taken us back to the eighteenth century to tell the story of its discovery. Messier 7, however, is an exception. It is popularly known as the Ptolemy Cluster, because he was the first to identify it.
In the year 130 of our era, Ptolemy cataloged this open cluster in his work Almagest. He described it as "a nebulous cluster behind the sting of Scorpio." It is the first object in the Messier catalog, which had already been discovered in antiquity.
Messier 7 is one of the most remarkable objects of its kind in the whole night sky. It is a large and luminous cumulus, known since Antiquity, because it can be detected with relative ease, and also has been cataloged as NGC 6475. The field of stars on which it stands, very rich, together with a certain dispersion of the stars of the cumulus.
Messier 7 is an open cluster (we call it open because the stars that compose it are not necessarily concentrated in its center) are about 80 stars of different magnitudes, at a distance of 800 to 1,000 light years from Earth. They occupy an area of 18 - 25 light years and were born at the same time about 220 million years ago (ie about 10 million years after the dinosaurs appeared on our planet), but despite having formed at the same time, these stars have evolved in very different ways.
More details here: Messier 7
The star cluster Messier 7. Image source: (2)
Messier 7. Image source: (3)