Which Milky Way globular cluster was first discovered by Abraham Ihle in 1665? It was Messier 22.
Messier 22, also called M22, is a globular cluster in the constellation Sagittarius, near the Galactic bulge. Johann Abraham Ihle discovered it in 1665 while observing Saturn. Like many early telescopic observers, he described the object as a nebulous patch rather than recognizing it as a vast, gravitationally bound swarm of stars.
Charles Messier added M22 to his catalog of comet-like objects in 1764. The cluster is also known as NGC 6656 or the Great Sagittarius Cluster. It is among the brightest globular clusters visible in the night sky and is about 10,600 light-years from Earth.
M22 is not the same as M13, the famous Great Globular Cluster in Hercules, or M15 in Pegasus. Its later scientific importance includes a planetary nebula and evidence for stellar-mass black holes. Astronomer Harlow Shapley studied M22 in 1930, helping establish its dense stellar core and large population of stars.