In 1999, the remains of an exploded star—the supernova remnant Cassiopeia A—was among the first objects on which the spaceborne Chandra telescope trained its X-ray eye. Chandra has been following these stellar leftovers ever since. Now, a decade of detection has produced a time-lapse movie of the evolution of the supernova remnant. It has been expanding since 1680, when its precursor star exploded.
Astrophysicists have also used the data from Chandra and other telescopes to reconstruct the first 3D multiwavelength fly-through of a supernova remnant. The reconstruction shows that the material from the outer layers of the star ejected radially, resulting in Cassiopeia A having an overall spherical shape. Scientists think the inner parts of the star were ejected as pointed jets. The central star then collapsed to form a dense neutron star at the center of the stellar remains. By mapping these evolutionary stages, astronomers can better understand how stars evolve and die.