M 13 is the most prominent Globular Cluster in the Northern Hemisphere and is a naked eye object in dark sky locations. M13 was first discovered by Halley of comet fame in 1714. The cluster contains an estimated several hundred thousand to 1 million stars, is 21,000 ly distant and is approximately 160 ly in diameter. The photograph suggest the central core is densely packed but that is an illusion due to the vast distance. the central core probably has a density of 1 star per cubic light year. A visitor to the core would find a nighttime sky filled with brilliant stars. (Burnham)
This type object is about the only deep space object that is more beautiful in the telescope eyepiece than in a photograph.