Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2014 June 17 http://www.youtube.com/watch?feature=player_embedded&v=93L0IEbUJsk V838 Light Echo: The Movie Image Credit: ESA, NASA, Hubble Space Telescope; Music: The Driving Force (Jingle Punks) Explanation: What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon suddenly became one of the brightest stars in the entire Milky Way Galaxy. Then, just a few months later, it faded. A stellar flash like this has never been seen before -- supernovas and novas expel a tremendous amount of matter out into space. Although the V838 Mon flash appeared to expel some material into space, what is seen in the above eight-frame movie, interpolated for smoothness, is actually an outwardly moving light echo of the flash. The actual time-span of the above movie is from 2002, when the flash was first recorded, to 2006. In a light echo, light from the flash is reflected by successively more distant ellipsoids in the complex array of ambient interstellar dust that already surrounded the star. Currently, the leading model for V838's outburst was the orbital decay and subsequent merging of two relatively normal stars. V838 Mon lies about 20,000 light years away toward the constellation of Monoceros, while the largest light echo above spans about six light years in diameter.
It's hard to wrap your mind around the significance and scale of that. I gotta second Yuri's comment; that was FUCKING cool!
It is the scale that's mind-boggling and so easy to overlook. We're in danger of becoming blase not only about the size and significance of such events, but also that we have the ability to film it in such incredible detail. MelT