Thousands of stars sparkle in this Hubble Space Telescope image of the core of Messier 10, a globular star cluster in Ophiuchus, the serpent bearer. The cluster contains hundreds of thousands of ancient stars, although a few look much younger (the blue stars in the image). Such stars have stolen gas from companion stars, or perhaps merged with them, revving up their nuclear reactions and making them appear younger. The cluster is about 15,000 light-years away, and is an easy target for binoculars on July evenings. [NASA/ESA/STScI]