EnlargeNASAThis image shows a dazzling display of star formation in the galaxy NGC 4214, which is located about 13 million light-years from Earth. "The youngest of these star clusters are located at the lower right of the picture, where they appear as about half a dozen bright clumps of glowing gas. . . . Moving to the lower left from the youngest clusters, we find an older star cluster . . . . The most spectacular feature in the Hubble picture lies near the center of NGC 4214. This object is a cluster of hundreds of massive blue stars, each of them more than 10,000 times brighter than our own Sun. A vast heart-shaped bubble, inflated by the combined stellar winds and radiation pressure, surrounds the cluster. The expansion of the bubble is augmented as the most massive stars in the center reach the ends of their lives and explode as supernovae."