Globular M13

Great Globular Cluster in Hercules

M13 was discovered by Edmond Halley in 1714, and catalogued by Charles Messier on June 1, 1764.

Less than half way from Arcturus to Vega, four bright stars in the constellation of Hercules form the Keystone. M13 can be seen in the middle of Zeta Herculis and Eta Herculis. Only telescopes with a great light-gathering capability can best show the Hercules Globular Cluster. M13 is not clearly visible to the naked eye. With a low-power telescope, the Messier 13 looks like a comet. The cluster can be seen all year long, on some nights more than others. However, in the months of August and September it brightens the sky for a longer period of time.