"V838 Mon: the movie
The Hubble Space Telescope (HST) has just released another couple of images in a series of the object V838 Monocerotis. V838 Mon as it is known to its friends is a very strange variable star that underwent a sudden outburst back in 2002. It temporarily became 600,000 times more luminous than our Sun although with it being about 20,000 light years away it didn't outshine the Sun in the sky! What makes this particular outburst quite spectacular is that we can see a light echo; just like a sound echo in a cave, the light is being scattered from clouds of interstellar dust. That means that as time goes on we get to see different parts of the dust clouds illuminated. This makes for a very cool probe of the dust and makes a beautiful series of images as the shell of light expands outwards."
See the whole series of images here:
http://www.strudel.org.uk/blog/astro/000541.shtml