The NASA/ESA Hubble Space Telescope has observed many star clusters. As well as being scientifically interesting, these clusters produce stunning images, appearing like sparkling baubles in the sky. <br /> <br />This episode of the Hubblecast looks at how Hubble has studied and imaged these beautiful objects, also introducing a striking new image of Messier 15, one of the oldest globular clusters in our skies. This is the best ever image of this cluster, which contains over 100 000 stars, a planetary nebula known as Pease 1 (otherwise named PN Ku 648 or Kürster 648), and something more exotic: at its core, it is thought to host a rare type of black hole. <br /> <br />Credit: ESA/Hubble
