Ripples of supernova remnant SNR 0509-67.5. The ripples, as well as the greater nebula, were imaged in unprecedented detail by the Hubble Space Telescope in 2006 and again late last year. The red colour was recoded by a Hubble filter that left only the light emitted by energetic hydrogen. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Acknowledgment: J. Hughes (Rutgers U.)