The radiation from 2,500 young stars excites the atoms causing them to emit radiation themselves. This view of the very center of the Rosette Nebula spans 15 light years across. Credit: NASA/ESA Hubble Space Telescope
A NASA/ESA Hubble Space Telescope (HST) view of the magnificent spiral galaxy NGC 4603, the most distant galaxy in which a special class of pulsating stars called Cepheid variables have been found. It is associated with the Centaurus cluster, one of the most massive assemblages of galaxies in the nearby universe.