Deep Sky
NGC 6715

Globular Cluster
Constellation:  Sagittarius
This hunk of stars-shine, was discovered by Messier in 1778.
This cluster for quite a while was thought to be part of the Milky Way family of fine globulars and about 50,000 light-years away from us.  However, in 1994 things happened that now make astronomers think that it belongs to the Sagittarius Dwarf Elliptical Galaxy.   This makes M54 the first globular cluster to loose its citizenship and now declared a extragalactic alien!  Who knew!
Astronomers now feel that M54 is some 87,000 light-years away, with a 150 light-years across.  Not too shabby for a foreigner.  Not only that it is one of the denser globulars with type III rating.  Other information is that NGC6715 has a luminosity roughly 850,000 times that of our sun and contains a intermediate-mass black hole at its core. 
5 images stacked
10 sec