Messier 92 — Globular Cluster in Hercules

M92 is a bright globular cluster located about 26,700 light-years from Earth in the constellation Hercules. It is one of the oldest known globular clusters, with an estimated age of about 14.2 billion years — nearly as old as the universe itself. The cluster contains roughly 330,000 stars packed into a sphere about 109 light-years in diameter, with an extremely dense core. M92 is intrinsically a magnificent object, but it is perpetually overshadowed by its more famous neighbor M13, which lies just 9 degrees to the southwest in the same constellation. At magnitude 6.4, M92 is just at the threshold of naked-eye visibility from very dark sites.

Located about 6 degrees north of the Keystone asterism in Hercules, roughly between Pi and Eta Herculis. Despite being overshadowed by M13, M92 is a superb target in its own right. A 4-inch telescope at 100x reveals a bright, concentrated core with a grainy outer halo beginning to resolve into individual stars. An 8-inch telescope at 150-200x resolves stars throughout the cluster, revealing chains and arcs of stars radiating from the dense core. M92 has a more compact, concentrated appearance than M13, with a distinctly brighter core. It is worth comparing the two clusters in the same observing session. Best observed from May through September.

Discovered by Johann Elert Bode on December 27, 1777, six years before Messier independently found it and added it to his catalog on March 18, 1781. William Herschel was the first to resolve its stars in 1783. M92 is one of the oldest objects with a well-determined age, and its ancient stellar population has been extensively studied to constrain models of the early universe and stellar evolution. It lies on the precessional path of Earth's north celestial pole and will become the 'North Star cluster' around the year 16,000 AD.