Discovered by Abraham Ihle in 1665.

Messier 22, also cataloged as NGC 6656, was the first globular cluster to be discovered.  Globular clusters contain some of the oldest stars in our galaxy and are the objects of considerable study and research.  M22 is located in the constellation Sagittarius approximately 10,000 light years distance.  It is one of the brightest globular clusters observable from northern latitudes.  M22 is one of only four globular clusters containing a planetary nebula.  The infrared satellite observatory IRAS discovered a weak planetary in the cluster identified as IRAS 18333-2357.  Recent studies using data collected by the Hubble Space Telescope have identified a number of planet-sized objects moving among the cluster stars.  The masses of these objects have been determined to be about 80 times that of the Earth.  These "orphan planets" were discovered using a technique so-called micro lensing, i.e. the bending of light of background cluster stars.

¹https://www.nasa.gov/feature/goddard/2017/messier-22
²https://www.messier.seds.org/m/m022.html