Light echoes from an exploding star. Hubble Space Telescope image of an illuminated dust shell around the star v838 Monocerotis. This star underwent a massive brightening in January 2002, temporarily becoming the brightest star in the galaxy. The light from this outburst reflects from a series of dust shells around the star, which are thought to have been ejected during previous activity. The phenomenon allows study of the fine structure of the dust shells, which could help explain why the star behaves as it does. This image was taken on 8th February 2004 by the Advanced Camera for Surveys.