M22 Globular Star Cluster

As Sagittarius climbs into the Southern night sky, M22 hangs just above. This is a very remarkable globular star cluster as it is actually brighter than M13, a big and very bright favorite of amateur astronomers. In fact M22 is the brightest globular in our Northern hemisphere skies. Its fairly big too, at over 200 light years in diameter, it is estimated to contain over 70,000 stars. And its close, only 10,400 light years from Earth. One thing that makes it rather unusual is that it contains a planetary nebula, IRAS 18333-2357 or GJJC 1, discovered by the IRAS infrared satellite.