M9 - NGC 6333

Messier 9 (NGC 6333) is a globular cluster located in the constellation Ophiuchus, approximately 25,800 light-years from Earth. It is one of the nearer globular clusters to the galactic center, lying only about 5,500 light-years from the Milky Way's core, which means it is significantly affected by interstellar dust extinction that dims and reddens its light. The cluster contains an estimated 250,000 stars packed into a sphere roughly 90 light-years in diameter, and it shines at an apparent magnitude of about 8.4. M9 was discovered by Charles Messier on May 28, 1764, who described it as a faint nebula without stars. The cluster was not resolved into individual stars until William Herschel observed it with his larger telescopes in the late 18th century. M9 is among the more challenging Messier globular clusters for amateur observers due to its relatively faint magnitude and small apparent size of about 12 arcminutes. Through binoculars it appears as a small, fuzzy spot, while a telescope of at least 6 inches is needed to begin resolving stars around its periphery. The cluster's core remains tight and unresolved in most amateur instruments. Hubble Space Telescope images have revealed the cluster's stellar population in stunning detail, showing the characteristic red giant and horizontal branch stars expected for its ancient age of approximately 12 billion years. M9's proximity to the galactic center makes it an important object for studying the tidal effects of the Milky Way's gravitational field on globular cluster dynamics.

Contains approximately 250,000 stars within 90 light-years diameter, located 25,800 light-years from Earth and only 5,500 light-years from the galactic center.