M13 is the brightest globular cluster in the Northern Hemisphere and has approximately 300,000 stars where in these relatively crowded quarters the average separation is around one light year apart. It lies 23,000 ly from the Earth in Hercules. Backyard 6/20/2020 with a 16″ LX200 scope, ZWOASI071 MC, Pixinsight and Photoshop. The big radio telescope at Arecibo Observatory sent a message to this cluster in 1974. Click on Message to M13