The Great Globular Cluster in Hercules or M13.
It was discovered by Edmond Halley in 1714, (the same who discovered Halley's comet) and was later catalogued by Charles Messier on June 1, 1764, in his list of objects that are not comets. With an apparent magnitude of 5.8, it is barely visible with the naked eye on a very clear night, and consists of a cluster of about 300,000 stars, that rotates our milky way galaxy at a distance of 25,100 light-years away from us and has a diameter of about 145 light-years.
An globular cluster, such as M13, is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. Globular clusters, which are found in the halo of a galaxy, contain considerably more stars and are much older than the less dense galactic, or open clusters, which are found in the disk. Globular clusters are fairly common; there are about 150 known globular clusters in the Milky Way.
The nearby blue galaxy is NGC 6207 and is a 12th magnitude edge-on galaxy that lies 28 arc minutes north east. This galaxy has an intermediate orientation as seen from here, and lies some 30 million light years away from us. That's nearly 1200 times farther away than M13. Consider that this galaxy almost certainly has its own globular clusters, much like M13, only at that distance they would be as faint.
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