December 4, 2008 - Hubble catches an instantaneous glimpse of many hundreds of thousands of stars moving about in the globular cluster M13, one of the brightest and best-known globular clusters in the northern sky. This glittering metropolis of stars is easily found in the winter sky in the constellation Hercules and can even be glimpsed with the unaided eye under dark skies. Near the core of this cluster, the density of stars is about a hundred times greater than the density in the neighborhood of our sun. These stars are so crowded that they can, at times, slam into each other and even form a new star, called a blue straggler. The brightest reddish stars in the cluster are ancient red giants. These aging stars have expanded to many times their original diameters and cooled. The blue-white stars are the hottest in the cluster.