Messier 13 - globular cluster in Hercules

Messier 13 (also known as M 13 from its position in the Messier Catalog, or as NGC 6205, or the Hercules Globular Cluster ) is a globular cluster visible in the constellation of Hercules. It is the brightest globular cluster in the northern hemisphere and third brightest in the entire sky. Easily visible to the naked eye, M13 has an apparent magnitude of 5.8 and an angular diameter of 23'. If we consider its distance from Earth of 23,157 light-years, its real diameter should be about 165 light-years. M13 contains hundreds of thousands of stars, the brightest of which is of 11.95 magnitude. Around its nucleus, the stars are about 500 times more concentrated than around of the Solar System . The age of M13 has been estimated between 12 and 14 billion years. Appearing so bright at such a great distance, its actual brightness is very high, more than 300,000 times that of the sun. Its radial speed is about 250 km / s approaching Earth. This motion results from the combination of three different speeds: the rotation of the Galaxy, the Sun's motion through space, and the motion of the cluster around the galactic center. Magnified crop only of the cluster can be seen below:

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