Mosaic of images of 12 globular clusters ranked in order of increasing dynamical age, as measured from the observed radial distribution of their blue straggler stars. From top left to bottom right: ... more 
Mosaic of images of 12 globular clusters ranked in order of increasing dynamical age, as measured from the observed radial distribution of their blue straggler stars. From top left to bottom right: omega Centauri, NGC 288, M55, NGC6388, M4, M13 less 
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SPACE.com | Photo By F.Ferraro (University of Bologna), NASA, ESA
Wed, Dec 19, 2012 1:12 PM EST