Light Echoes

In a light echo, light from the flash is reflected by successively more distant rings in the complex array of ambient interstellar dust that already surrounded the star. V838 Mon lies about 20,000 light years away toward the constellation of the unicorn (Monoceros), while the light echo above spans about six light years in diameter.

I don't quite understand the science (which is further explained at Astronomy Picture of the Day); blogged primarily because of the beauty of the image. Click photo to enlarge.