Messier 26 — Open Cluster in Scutum

M26 is a small, moderately rich open cluster in the constellation Scutum, located about 5,000 light-years from Earth. It spans roughly 22 light-years across and contains around 90 stars, with an apparent diameter of about 15 arcminutes. The cluster is estimated to be around 89 million years old. One of M26's most distinctive features is a region of lower star density near its center, likely caused by an intervening cloud of interstellar dust that obscures some of the cluster's members. The brightest star in the cluster is of about magnitude 11.9, making this one of the fainter Messier open clusters.

Located in the rich Milky Way star fields of Scutum, about 1 degree south-southeast of Delta Scuti. In binoculars, M26 is difficult to distinguish from the dense background star field. A 4-inch telescope at 80-100x reveals a compact group of faint stars with a noticeable dip in star density near the center. Higher magnification (150x+) resolves more of the fainter members. The cluster benefits from dark skies since the Scutum star cloud provides a confusing backdrop. Best observed from July through September when Scutum is well-placed in the evening sky.

Discovered by Charles Messier on June 20, 1764. Messier described it as a cluster near Eta and Omicron Scuti, without nebulosity. William Herschel later resolved the cluster into individual stars using his larger telescopes. M26 has received relatively little scientific attention compared to other Messier clusters, partly due to its small size and location in a crowded star field.