Light echoes around star V838 Monocerotis, Hubble Space Telescope image. This star underwent a massive brightening, or nova, in 2002. Since then, the light released by this event has illuminated a series of shells of gas and dust that surrounded the star. The shells are thought to have been formed by ejections from the star in its past. The 2002 nova is unusual in that the star's outer layers were not ejected in the event, it merely grew enormously in size. Studying the shells may increase understanding of the star's behaviour. This star is 20,000 light years from Earth, in the constellation Monoceros. This image was obtained on 9 September 2006, with Hubble's Advanced Camera for Surveys instrument.