M22 is one of the nearer globular clusters to
Earth at a distance of about 10,600 light-years away. It spans
32' on the sky which translates to a spatial diameter of 99 ± 9
light-years. 32 variable stars have been recorded in M22. It is
projected in front of the galactic bulge and is therefore useful
for its microlensing effect on the background stars in the
bulge. Despite its relative proximity to us, this metal-poor
cluster's light is limited by dust extinction, giving it an
apparent magnitude of 5.5 making it the brightest globular
cluster visible from mid-northern latitudes . However, due to
its southerly declination, M22 never rises high in the sky and
so appears less impressive than other summer sky globulars such
as M13 and M5.
