Messier 7 — Open Cluster in Scorpius

M7, also known as Ptolemy's Cluster, is one of the most prominent open clusters in the sky, located about 980 light-years from Earth in the constellation Scorpius. It spans about 25 light-years across and contains roughly 80 stars brighter than magnitude 10, with the total membership estimated at about 100 stars. At magnitude 3.3, it is one of the brightest open clusters visible. The cluster is estimated to be about 200 million years old, and its brightest stars are blue-white giants and subgiants.

Located about 5 degrees northeast of the Scorpion's stinger star Shaula (Lambda Scorpii). Easily visible to the naked eye as a bright, large patch in the Milky Way. Binoculars give a stunning view, resolving dozens of bright stars scattered across about 1.3 degrees of sky. A telescope at low power (25-40x) provides the best view, framing the whole cluster with scattered bright stars against a rich Milky Way background. Higher magnification loses the visual impact. Best from June through August.

Known since antiquity. Ptolemy described it around 130 AD as a 'nebulous cluster following the sting of Scorpius,' making it one of the first deep-sky objects ever recorded. Charles Messier added it to his catalog in 1764. It was one of Messier's most southerly observations from Paris.