The Blue Snowball Nebula is the last gasp of a dying star. The star has expelled its outer layers of gas into space, leaving behind only its hot core, which is becoming a white dwarf. Ultraviolet energy from the core makes the expelled gases glow. The blue color comes from oxygen in the nebula. The nebula is about 6,000 light-years away, in Andromeda. [NASA/ESA/A. Hajian (University of Waterloo)]