V838 Monocerotis - NASA/ESA via Hubblesite
Alan Taylor of Boston Globe's The Big Picture Blog, one of the neatest blogs around on the Web, has a truly neat post about the most amazing images captured by the Hubble Space Telescope: Link - Thanks Tiny Dancer!
This one above is the "light echo" of the explosion of V838 Monocerotis, about 20,000 light years from the sun. From Wikipedia:
V838 Monocerotis (V838 Mon) is a variable star in the constellation Monoceros about 20,000 light years (6 kpc) from the Sun. The star experienced a major outburst in early 2002. Originally believed to be a typical nova eruption, it was then realized to be something completely different. The reason for the outburst is still uncertain, but several theories have been put forward, including an eruption related to stellar death processes and a merger of a binary star or planets.
V838 Monocerotis was also dubbed the "Firefox" star, because of its similarity to the popular browser's logo (previously on Neatorama)