M9

M9 is a moderately bright globular cluster in Ophiuchus, about 25,800 light-years from Earth. It lies near the center of the Milky Way and is partially dimmed by interstellar dust, which reddens its light. The cluster contains roughly 250,000 stars packed into a sphere about 90 light-years across.

Located about 3.5 degrees southeast of Eta Ophiuchi. Appears as a small, round fuzzy patch in binoculars. A 6-inch telescope shows a bright core with a diffuse halo, but resolving individual stars requires 8 inches or more and high magnification. A nearby dark nebula (Barnard 64) is visible to the east. Best observed from June through August.

Discovered by Charles Messier on May 28, 1764. He described it as a nebula without stars. William Herschel resolved individual stars in 1784. Due to its southerly declination and proximity to the galactic center, it was less studied than many other globulars until modern times.