Avatar may be breaking box office records here on Earth, but another 3-D event is creating a stir beyond our solar system. Astronomers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, have used phenomena called light echoes to reconstruct in three dimensions the explosive death of a giant star whose light originally touched our world 330 years ago. Such echoes occur when the supernova's bright flash bounces off of dust clouds in various locations around the galaxy. Like strategically placed mirrors, the reflections can convey subtle details about these titanic explosions. In the case of this star, called Cassiopeia A, the 3-D reconstruction reveals that some parts of the blast traveled nearly 15 million kilometers per hour faster than others (green areas), giving Casiopeia A's demise a rather non-spherical appearance—something that can be seen here without the aid of special glasses.